Ancient History & Civilisation

Chapter Five

“Colonnades about It in Very Great Numbers”: The Porticoes of the Campus Martius

With the onset of winter in 169 B.C.E., Perseus, the King of Macedonia, was wary that the forces of Rome would attack his poorly defended kingdom. Earlier that year, envoys from Rome had traveled through the Peloponnese and Aetolia south of Macedonia, shoring up the support of allied cities. Now, Perseus expected the worst.1 Knowing that the Illyrians along the modern Dalmatian coast to his west had been wavering in their support for Macedonia and could provide Rome with a pathway to his kingdom, Perseus decided to take the offensive. Waiting until the winter solstice when the snows protected him from invasion across the western passes from Thessaly, Perseus invaded Illyricum, capturing a Roman garrison.2 With one success under his belt, Perseus continued to attack and overran eleven other Roman forts.3 A powerful Roman response was now assured.

With war against the Macedonians clearly on their minds, the Romans chose their two consuls and six praetors for the upcoming year. Lucius Aemilius Paullus was elected consul and directed to lead the forces against Macedonia. Gnaeus Octavius was chosen as a praetor and tasked with conducting Rome's naval operations.4 In April 168 B.C.E., shortly after the Latin Festival concluded, the fleet departed east.5 Octavius's warships traveled up the east coast of Greece to Heracleum, Meliboea, and the island of Samothrace.6 At these locations, Octavius would have seen extraordinary Hellenistic architecture, particularly at Samothrace with its remarkable sanctuary complex composed of altars, a circular theatrical area, banquet rooms, a monumental gate, and a colonnade.7Approximately 104 meters long, the Samothrace colonnade was one of the largest in Greece. Two aisles were created by two rows of columns, one down the center of the enclosed space and the other along its eastern edge.8 The western length and the ends were enclosed. The colonnade sat next to a fountain crowned by the famous Nike of Samothrace, now in the Louvre. Situated on a hill, the marbled colonnade would have afforded Octavius with a panoramic view across the entire complex.9 It was at Samothrace that Octavius captured the King of Macedonia, placing Perseus in his flagship and sending him on to the consul Aemilius Paullus camped on the Macedonian mainland.10 With the last of the Antigonid kings captured and the Third Macedonian Warover, Octavius loaded his ships with plundered bronze shields, statues, paintings, and vessels made of gold, silver, bronze, and ivory and headed back to Rome.11

In a procession of ships, first the conquered and then the conquerors traveled up the Tiber to Rome. Prisoners now, Perseus and his family were followed by the triumphant consul Aemilius Paullus, sailing in a captured royal galley with sixteen banks of oars. A few days later Gnaeus Octavius landed with his fleet and the Macedonian treasure.12 The victorious consul and praetors were each awarded a triumph. In contrast to the triumph of Aemilius Paullus with its procession of the defeated Macedonians and their millions of sesterces in treasure, Octavius's triumph was a relatively simple affair without prisoners or captured loot.13 Although his celebration was modest, Octavius used his manubiae to create a stone memorial to his role in the defeat of the Macedonian king. As many generals before him had done, Octavius chose to erect his structure in the Campus Martius, and like Fulvius Nobilior and M. Aemilius Lepidus a decade earlier, he selected more specifically the Circus Flaminius, where the edifice would be passed by future triumphant processions. Indeed, during the intense debate in the Senate over whether or not to award a triumph to Aemilius Paullus, the senators recognized that if the parade were not granted, the royal prisoners and their treasure would sit in the Circus Flaminius and go no farther.14 As a starting point for triumphal display, this was a prime location for a general's commemorative building. Departing from the precedents of the earlier consuls who regularly commissioned temples as part of their triumphal celebrations, Octavius erected a colonnade (Porticus Octavia) in the Circus Flaminius.15 Although no ruins of Octavius's colonnade remain, it likely stood on the northeastern side next to the Temple of Neptune, an appropriate location to honor an admiral's victory (Plan 2, No. 13).16

Octavius's colonnade marked the first use of a colonnade in Rome as a war memorial, and it was designed to impress. It certainly caught the attention of Pliny the Elder, who noted that the structure's columns had capitals of Corinthian bronze and it was appropriately called the Corinthian portico. Velleius Paterculus records the portico as “the most splendid of all.”17 Why Octavius chose to construct a colonnade is unrecorded, but it is tantalizing to conjecture that the enormous and well-sited one at Samothrace influenced his choice.18 Pliny's description of Octavius's colonnade as a double portico (porticum duplicem), a phrase that might refer to the number of aisles, wings, or stories, supports the supposition.19 The single-wing colonnade on Samothrace contained a double row of columns, although any number of Hellenistic colonnades the praetor observed during the campaign could have served as models. The Romans in the Third Macedonian War were allied with Eumenes II, King of Pergamon, who constructed in his capital a decade earlier an L-shaped colonnade with two stories and a double aisle.20 Whatever the Roman structure's ultimate architectural inspiration, Octavius would have seen numerous examples throughout the Greek world that were built as monuments to the greater glory of their patrons.21 The significance of Octavius's commemorative colonnade was not lost on his descendant Octavian, Rome's soon-to-be emperor Augustus. In 33 B.C.E., Octavian rebuilt the colonnade and placed within it the Roman standards recaptured from the Illyrians, the tribe that Perseus had attacked a century and a half earlier.22 It was apparently Octavian's first gift to the Roman people not begun by Julius Caesar and was worthy of highlighting in the Res Gestae.23 By the time of Augustus, however, extraordinary colonnades existed throughout Rome. Monumental colonnades had become, as John Senseney noted, “a building block of Republican and Imperial urbanism.”24 This new trend was most evident on the Field of Mars.

Although Gnaeus Octavius's colonnade was the first such structure erected as a victory monument, it was not actually the first building of this type in Rome, nor even the first in the Campus Martius. That distinction was held by one built by the consul under whom Octavius served. In 193 B.C.E., Aemilius Paullus along with M. Aemilius Lepidus in their roles as curule aediles oversaw the construction of a covered walkway that ran from a gate in the Servian Wall, the Porta Fontinalis, to the area of the Altar of Mars in the Campus Martius (a Porta Fontinali ad Martis aram).25 Although no definitive traces of this colonnade have been identified in the Campus Martius, it appears to have been constructed as a ceremonial walkway for the ritual journey to the Altar of Mars by the censors whose headquarters, the Atrium Libertatis, were located in the vicinity of the Porta Fontinalis.26 As the altar likely stood in the Villa Publica, the walkway probably crossed the brook that ran through the southern Campus Martius, the Petronia Amnis, and, thus at that point was a covered bridge.27 Arriving at the altar through the colonnade, the censors would have conducted the lustrum at the conclusion of the census.28 A costly undertaking financed from fines collected for illegal grazing, the walkway may have provided the name of the southern portion of the Campus Martius known as the Aemiliana.29

In the same year that they authorized the construction of the porticus from the Porta Fontinalis to the Altar of Mars, the two curule aediles caused a utilitarian structure to be built down on the eastern bank of the Tiber River southwest of the Aventine by the Porta Trigemina. Called the porticus extra Portam Trigeminam, it likely served the purpose of sheltering pedestrians and traders with no significance as a monument.30 Several other utilitarian structures called porticoes were built in the same time period and were similar in purpose, including one built by M. Fulvius Nobilior in the vicinity of the Navalia on the bank of the Tiber in 179 B.C.E., the same year that he constructed the Temple of Hercules in the Circus Flaminius.31 Octavius's colonnade constructed a decade later moved the architectural form in a new direction in terms of both funding and purpose. Later victorious republican generals and then emperors followed Octavius's example.

A colonnade of the type visible to a Roman during the Third Macedonian War was known in the Greek-speaking world as a stoa, a term that the Greeks used at first to describe a freestanding, single-wing, covered structure similar to the one at Samothrace, generally closed on one length by a solid wall, while open on the opposite side with one or more screens of columns.32 By the second century B.C.E., however, the term was applied to a variety of colonnaded structures throughout the Hellenistic world such as the L-shaped stoa at Corinth and the multileveled colonnades at Pergamon.33 Often located by religious sites, the stoa provided shelter from the elements and contained dedicatory inscriptions and sometimes statues in niches.34 Use of a lengthy colonnade as a connector road similar to Rome's first one, built a Porta Fontinali ad Martis aram, has few obvious Greek antecedents, and the covered walkways that proliferated throughout the Roman Near East are later in date.35

By the time of Augustus, the freestanding, single-wing stoa had given way, even in Greek cities, to colonnades more fully integrated with other structures and spaces.36 Employing the term stoai to describe the crowded collection of colonnades that littered the Campus Martius in the early decades of the first century C.E., the Greek-born geographer Strabo would have seen them employed as covered streets, attached to theaters, surrounding temples and parks on four sides (quadriporticus), and serving as art galleries and shopping spaces.37 Roman writers such as Pliny and Livy used the term porticus to describe these beautiful colonnades as well as the plainer brick arcades that lined the Tiber. Some inscriptions, such as Augustus's testament that were written in both Greek and Latin, employed the terms stoa and porticus, respectively, to describe the same structure.38 Here, the English term portico will be used interchangeably with colonnade to refer generally to the variety of gallery-like structures supported by columns along at least one side that proliferated throughout the Campus Martius from the second century B.C.E. onward.

The use of porticoes to memorialize the glorious deeds of their builders caught on in Rome. Two decades after Gnaeus Octavius constructed his colonnade, a second manubial portico was built at the southeast end of the Circus Flaminius. This one also honored a victory over the Macedonians. Constructed by Q. Caecilius Metellus Macedonicus following his annexation of Macedonia in 146 B.C.E., the Porticus Metelli served as a sacred precinct boundary, enclosing at least partially, and perhaps completely, the temples of Jupiter Stator and Juno Regina (Plan 2, Inset B).39 Not simply the structure but also the contents served to celebrate Metellus's achievements in the Fourth Macedonian War. The portico provided an appropriately grand setting for what J. J. Pollitt described as “one of the most famous and [he suspects] influential monuments of Hellenistic art” – a captured collection of twenty-five equestrian statues commemorating Alexander the Great's fallen comrades at the Battle of Granicus (334 B.C.E.), designed by Alexander's court artist, Lysippos.40 The statues were arranged facing the temples in the area between the Porticus Metelli and the two shrines. At some point after the portico's construction, perhaps in the early first century B.C.E., a seated bronze statue of Cornelia, mother of the Gracchi, was added to the space.41 It was one of the earliest publicly displayed statues of a woman in Rome.42

A few decades after the dedication of the Porticus Metelli, the siting of commemorative porticoes began to move north in the Campus Martius. In 110 B.C.E., the consul M. Minucius Rufus constructed a portico in the vicinity of the Largo Argentina sanctuary to honor his victory over a Balkan tribe.43 Later called the Porticus Minucia Vetus, this structure possibly was a quadriporticus completely enclosing about 5,000 square meters of the sacred area (Plan 3, Inset A).44

Until this point, porticoes had been used as military monuments and as defining elements of sacred spaces. One-half century later, a significant change occurred when the most famous portico in the Campus Martius, the Porticus Pompeii, was constructed west of the Porticus Minucia Vetus and just east of the Theater of Pompey (Plan 3, No. 25). Behind and attached to the theater's stage building, a rectangular walkway enclosing parkland more than 24,000 square meters in area was walled on its outer perimeter and supported by a colonnade on the inner sides.45 As Pompey found inspiration for his theater during his travels in Greece, so, too, he likely saw porticoes used in conjunction with theatrical spaces.46 The Augustan architect Vitruvius, who devoted an entire chapter to porticoes in book 5 of De architectura libri decem, associated Pompey's portico with colonnades in Athens, Smyrna, and Tralles that were related to theaters.47 Although Vitruvius praises the utilitarian benefits of a portico built near or behind a theater “so that when sudden rains interrupt the performances, the audience has a place to gather outside the theater, and the performers have a place to rehearse,” that purpose likely was of greater need for Greek theaters built into hillsides than for Pompey's freestanding theater with its protective stone superstructure.48 Built in conjunction with his theater, Pompey's quadriporticus provided strollers a delightful respite from the Roman sun and, we are told, a quiet spot for amorous assignations.49 Cut off from the noise of the urban bustle, visitors walking through the colonnade could view extraordinary examples of Greek paintings and sculpture lining the outer walls that were punctuated by rectangular and semicircular exedras.50 Although Metellus's portico was known for a statue of the noble Roman woman Cornelia, Pompey's colonnade housed a rare grouping of statues of females who have been described as courtesans but may have been women poets.51 Pliny listed numerous paintings by famous Greek artists Nikias, Pausias, and Antiphilusas having been displayed throughout the portico.52 Looking out through the spaces between the columns, visitors would have gazed upon a park that mimicked a sacred grove with uniformly trimmed plane trees growing in rows down the center of the open area, the expanse punctuated with fountains and sculpture; gold and purple textiles from Pergamon fluttered in the breezes.53

Vitruvius reports that apart from being visually pleasing, a quadriporticus such as Pompey's had distinct health benefits:

The central spaces between the porticoes and open to the sky should be adorned with gardens because open-air walkways are of great benefit to health: for the eyes, first of all, because the subtle and light air from green plants flows in as the body exercises and clears the vision, carrying off the dense moisture from the eyes and leaving the sight fine and the image sharp. Furthermore, as the body heats up by moving around the walkways, the air, sucking away moisture from the limbs, reduces fullness and diminishes them by dissipating whatever the body has absorbed beyond what it can bear.54

According to the Severan Marble Plan, another single-wing colonnade was connected to the northern side of Pompey's portico and possibly projected beyond the eastern edge.55 Opening north to the street instead of enclosing a courtyard, it would have provided a very different experience from the quiet stroll through the quadriporticus behind the attaching wall. As shown on the Marble Plan, the north-facing portico had two aisles with the inner aisle's columns set closer together and semicircular niches along the inner wall. The line of the roof extended past the outer row of columns. The remaining letters of its name [OSTYLVM] identified on the Marble Plan suggest that this was the Hecatostylon, the common name for the 100-columned structure that was destroyed in a firein 247 C.E. (Plan 3, No. 27, and Figure 24).56 Attached to but separated from Pompey's portico by its south wall, the Hecatostylon may have communicated with Agrippa's baths just to the north as well as with a park just west of the baths.57 The original formal name may have been the Porticus Lentulorum, a structure built either at about the time of the construction of Pompey's quadriporticus or in the early imperial era when Augustus was still encouraging Rome's great families to contribute beautiful architecture to the city.58 A portico built during Augustus's reign and containing statues of all nations (Porticus ad Nationes) stood in the area of the Theater of Pompey and possibly was the same structure as the Porticus Lentulorum and Hecatostylon.59 Pliny indicates that a statue of Hercules stood at the entrance to the Porticus ad Nationes, suggesting it was, in fact, a quadriporticus.60

24. Hecatostylon, Severan Marble Plan fragment (Stanford #39ac). (Photo: with permission of Forma Urbis Romae Project, Stanford University and Roma, Antiquarium Comunale)

Four decades after Pompey dedicated his Theatrum Pompei, Cornelius Balbus built his theater complex just to the southeast. Emulating the great general, he added a quadriporticus behind the scaenae frons. Identified in the fourth-century C.E. regionary catalogsas the Crypta Balbi, the three-sided structure enclosed a courtyard of approximately 6,800 square meters (Plan 3, No. 15). The meaning of the term crypta is uncertain, although it is thought that originally the complex was similar to a structure in Pompeii identified as a cryptoporticus that had a covered gallery with a series of windows surrounding a colonnaded walkway.61 There were niches in the external walls of the Crypta Balbi that were later filled with brick. Excavations have revealed an exedra on the east side of the complex, shown on the Severan Marble Plan with columns across the front (Figure 25). In a manner similar to the Porticus of Pompey, the exterior solid wall of the Crypta Balbi provided a more contemplative space than the colonnades that were open to the street. During the reign of Hadrian, the Crypta Balbi was rebuilt with a second story. The exedra on the east side of the portico was converted to a latrine.62

25. Theater of Balbus, Severan Marble Plan fragment (Stanford #30abc). (Photo: with permission of Forma Urbis Romae Project, Stanford University and Roma, Antiquarium Comunale)

At the same time that the Theater of Balbus and the Crypta Balbi were under construction, the sister of Augustus, Octavia, completed the rebuilding of the Porticus Metelli, a project initiated by her son Marcellus before his death in 23 B.C.E.63 The porticus was located just a few meters from the site of the theater later to be dedicated to Marcellus. While it is uncertain if the original Porticus Metelli was a quadriporticus, the Porticus Octaviae clearly had four sides serving as a sacred precinct boundary for the temples of Jupiter Stator and Juno Regina, as well as a shelter from the sun and rain. Following the same footprint as its republican predecessor, at least on the southern side, the Porticus Octaviae appears to have been much grander; its marble facade on the Circus Flaminiuswas marked by a monumental entrance staircase and gate (propylaeum) in the Corinthian order and arched openings in the walls that led to the interior, colonnaded walkways (Plan 3, Inset B).64 Today, the propylaeum is seen as projecting both within and without the line of the portico with four columns on each side (Plate X), but the design on the third-century Marble Plan shows six columns and no interior projection (Figure 26).65 Although the original Porticus Octaviae was constructed with a solid inner wall that hid the temples below the roofline from sight of those facing the structures from the Circus Flaminius, by the time of the Marble Plan the wall had been replaced with a row of columns allowing a clear view of the two temples behind the porticus.66 This would have created a significant alteration to the space, reincorporating the temples into the open and bustling Circus Flaminius. The entire quadriporticus appears to have been raised up on a podium, a design feature that often characterized sacred colonnaded precincts in both Greek and Roman architectural traditions.

26. Detail, Vat. Lat. 3439 f.23r. Porticus Octaviae enclosing the temples of Jupiter Stator and Juno Regina after the Severan Marble Plan (sixteenth century). (Photo: with permission of Biblioteca Apostolica Vaticana, with all rights reserved)

Plate X View west along the Porticus Octaviae in the direction of propylaeum

The quadriporticus framed 16,000 square meters comprising a complex that Pliny called the Octaviae opera. It included, in addition to the two temples, a library of both Greek and Latin works (bibliotheca Porticus Octaviae), an assembly space (curia) where, on at least one occasion, the Senate met, and lecture halls (scholae).67 Moreover, the complex was decorated with a wide array of celebrated paintings and sculptures, although it is uncertain if paintings were displayed in the portico itself, an issue that would have been resolved at the time the wall facing the Circus Flaminius was opened with columns. A famous painting of the Trojan princess Hesione by the Greek painter Antiphilus was displayed, and in keeping with the Alexander theme initiated with the installation of the Granicus Group in the portico's earlier iteration, one of the lecture halls within the complex reportedly displayed a painting of Alexander the Great and his father Philip with the goddess Athena, also by Antiphilus.68 Hercules, who was honored nearby in the Circus Flaminius with two temples, Hercules Musarum and Hercules Custos, was worshiped within the borders of Octavia's portico as well. Pliny notes that the Octaviae opera contained paintings by Androbius illustrating Hercules’ apotheosis and the story of King Laomedon, whose daughter Hesione was rescued by Hercules from Poseidon's wrath.69 A marble statue of Venus said to have been carved by Phidias and a Cupid by Praxiteles were located in the Octaviae opera, as well as statues of Aesclepius and Diana by Cephisodotus and Juno by Dionysius, all three of which appear to have stood inside the Temple of Juno Regina.70 In 80 C.E., the year after Pliny perished in the pyroclastic catastrophe at Pompeii, the Porticus Octaviae burned in the fire that swept through the Campus Martius. While it is known that the structure was rebuilt, most likely by Domitian and then, after another fire, by Septimius Severus and Caracalla, the fate of its famous art and library collections is unknown. The visible remains of thepropylaeum and columns are from the later reconstructions (Figure 27).71 The Porticus Octaviae illustrates well the intertwined functions of porticoes in the Campus Martius at the end of the first century B.C.E. As well as serving as a resplendent memorial to deceased members of the imperial family, a porticus could be equipped with galleries and spaces for political meetings, intellectual discussion, and the display of famous art collections.

27. Propylaeum of the Porticus Octaviae, south side. (Photo: Paul Jacobs)

Likely following the same line as the Porticus Metelli on the northern side of the Circus Flaminius and constructed about six years before the Porticus Octaviae replaced Metellus's structure, another quadriporticus surrounded the Temple of Hercules Musarum, defining the northern length of the circus in the late first century B.C.E. Built at approximately the same time that the second-century B.C.E. temple was restored in 29 B.C.E., the portico as well as the temple reconstruction work was financed by Augustus's stepfather, L. Marcius Philippus (Plan 3, Inset B).72 Described primarily as a picture gallery, and similar to the Porticus Octaviae next door, the porticus contained works by the painter Antiphilus, including a Father Liber, a young Alexander, and a Hippolytus terrified by a bull.73 As shown on the Marble Plan, the Porticus Philippi had, at least by the second century C.E., a wide double portico, with the columns along the inner edge standing closer together than those of the outer row.74 An outer wall enclosed the complex, obscuring the Hercules temple from the Circus Flaminius. If the Porticus Octavia (of Gnaeus Octavius) was in line with the Porticus Philippi and the Porticus Octaviae, then the three colonnades would have stretched for about 290 meters along one side of the Circus Flaminius and presented a certain uniformity to grouped sacred precincts.75 With a theater at its southern edge, two major porticoes filled with extraordinary Greek art along its eastern line, and backing on another theater and portico complex, the Circus Flaminius was, in the early imperial era, an important cultural node in the Campus Martius. These structures helped to define a space that had previously been unconfined and presented a kind of viewing platform along the edges of the space for witnessing the assembly of triumphal chariots and wagons.

Around the Theater of Marcellus to the southeast, colonnades continued along the base of the Capitoline Hill on the east side of the Forum Holitorium. On the west side of the vegetable market, the columned pronaos of each of the three temples of Janus, Spes, and Juno Sospita lined up such that they provided the suggestion of a continuous portico, giving a visitor the sense of a colonnade on both sides (Plan 2, Inset D).76 Unifying space through continuous colonnades, and particularly with uniform proportions, was a technique that Vitruvius encouraged. His ideal portico consisted of a colonnade with the width of the two interior aisles equal to the height of the outside columns. As the portico roof sloped, the interior columns were to be higher by one-fifth than the exterior columns.77 The variety of colonnades found in Rome indicates that the ideal principles of Vitruvius were not always followed and, as with the temples in the Forum Holitorium, the sense of a colonnade could be conveyed by simply lining up columned porches.

The boom in portico construction in the late first century B.C.E. extended north of the Circus Flaminius to the central Campus Martius. Soon after Pompey dedicated his theater, Julius Caesar proposed turning the nearby and centuries-old voting precinct, the Saepta, into a marbled space for casting ballots surrounded by a mile of porticoes.78 A perimeter of that length would have enclosed a space six times the space within Pompey's portico and one-tenth of the entire Campus Martius. Ultimately, however, the Saepta Julia was completed by Agrippa with a perimeter half the length of that proposed by Caesar and enclosing just half again as much space as Pompey's portico.79 The precinct had porticoes running down the east and west sides, but not on the north or south ends. Although Cassius Dio records that the Saepta was surrounded by porticoes, other evidence indicates that the southern end was adjoined to the Diribitorium by a broad corridor without columns and the northern end had a lobby separated from the voting hall by a connecting wall with eight doorways through which voters could enter.80 The Porticus Argonautarum followed the western line, and the Porticus Meleagri stood along the eastern line. Separated by the 120-meter width of the Saepta, the two porticoes would have been at their longest 310 meters, the length of the voting precinct (Plan 3, Nos. 8 and 9).81

Completed by Marcus Agrippa in approximately 25 B.C.E., the Porticus Argonautarum was named after a painting depicting the story of Jason and the Argonauts displayed somewhere inside or in the vicinity of the walkway.82 Later references in Martial'sEpigrams suggest the portico was immediately rebuilt after the devastating conflagration in 80 C.E. and remained very popular for strolls and informal meetings, as well as a shopping area for luxury goods.83 It is possible that the Porticus Argonautarum served similar functions in Agrippa's day; despite being an independent structure, there is no doubt it was also used on occasion as a place for shelter and gathering during the political and entertainment activities that are recorded to have taken place in the Saepta Julia. Although its dimensions and overall design remain uncertain, a surviving portion of its western wall next to the later built Hadrianic Pantheon indicates that it was constructed of brick-faced concrete and covered in marble with regularly placed rectangular niches that possibly held statues (Figure 28).84 Its close proximity to the east side of the Pantheon's drum suggests that pedestrian traffic between the Saepta and Hadrian's structure funneled through the colonnade.

28. Portion of the western wall, Porticus Argonautarum. (Photo: Paul Jacobs)

Though the Porticus Meleagri is identified through three fragments of the Marble Plan and mentioned in the late antique regionary catalogs, the date of its construction is not secure. However, given the numerous illustrious building projects nearby – the Saepta Julia (dedicated in 26 B.C.E.), Porticus Argonautarum (ca. 25 B.C.E.), the Diribitorium (dedicated in 7 B.C.E.), the Pantheon (ca. 27 B.C.E.), and Baths of Agrippa (ca. 25 B.C.E.) – the Porticus Meleagri was likely constructed during the final decades of the first centuryB.C.E. as part of imperial efforts to monumentalize the area and specifically to serve a the eastern border for the Saepta Julia. Like the Porticus Argonautarum, the Porticus Meleagri probably derived its name from publicly displayed artwork, in this case paintings or sculptures illustrating the myth of another of the Argonauts, Meleager.85

During the late republican and early imperial era, the Field of Mars was not singular as a site for the construction of spectacular porticoes. Perhaps the most important use of quadriporticus architecture in the city was to define the perimeters of the imperial fora located within the pomerium to the southeast of the Campus Martius. Enclosing temples, lawcourts, and public administrative space, the porticoes of the Forum Iulium and Forum Augustum, and still later the Forum Traiani and Forum Transitorium, helped to create a unified urban complex in marble.86 Together, the Forum Iulium and Forum Augustum enclosed more than 22,000 square meters within their colonnades, which, while impressive, is still but three-fifths of the area enclosed by the Saepta Julia alone.87Indeed, when all of the major quadriporticus constructions with known dimensions and extant at the time of Augustus are considered, those in the Campus Martius enclosed as much as three-fourths of the colonnaded space or more than 100,000 square meters.88These figures do not include the single-wing porticoes such as the Hecatostylon that, when added, helps explain why Strabo singled out the Field of Mars for its numerous colonnades.

The emperors after Augustus continued to populate the Campus Martius with porticoes. Sometime in the mid- to late first century C.E., a second Porticus Minucia was constructed. Known from the regionary catalogs as the Porticus Minucia Frumentaria, this portico is likely the quadriporticus indicated on the Marble Plan just east of the Largo Argentina and possibly was an extension of the earlier Porticus Minucia Vetus (Plan 4, No. 10).89 Surrounding an earlier built temple, perhaps the Temple of the Nymphs, the portico possibly served a mostly utilitarian function as a grain distribution point. Those entitled to collect a monthly wheat dole came to one of forty-five stations either within the porticus or perhaps in the arcade on the west side to wait their turn.90 In a manner similar to the entertainment sites described in Chapter 4 and the baths to be discussed in Chapter 6, the portico helped assure that the imperial Campus Martius would attract a constant flow of visitors to the once open field. While not likely ever used as a place of refuge, a large, centrally located porticus where provisions could be stored would have met the practical safety aspects of an enclosed colonnade as articulated by Vitruvius, who noted that they provided protection in time of war and that during emergencies they could be used for the allocation of rations.

During such emergencies, the walkways are opened up and rations are allocated to individuals according to their tribes. Thus open-air walkways offer two excellent advantages: a place of health in peacetime, and, secondly, a place of safety in time of war. For these reasons the layout of walkways, put in not only behind the scene building of the theater, but also in the precincts of all the gods, can offer great benefits to cities.91

Possibly at the same time as the construction of the Porticus Minucia Frumentaria, the emperor Domitian constructed a less utilitarian colonnade just east of the Saepta Julia in what was left of the now shrunken Villa Publica (Plan 4, No. 9). Known as the Divorum, the portico as shown on the Marble Plan measured 15,000 square meters and was entered through a triple arch on the north and a less definable columned entrance on the south. The colonnade enclosed two small facing temples on the northern edge as well and, similar to the portico of Pompey, may have had rows of large trees along the eastern and western sides.92 Adjacent to the Saepta Julia on the north, the emperor Hadrian enclosed a temple to the memory of his mother-in-law, Matidia, within a portico (Plan 4, No. 13). As represented on a second-century C.E. medallion, the portico had a high colonnade on the first story and a second story that may have been vaulted. It was likely a quadriporticus with walls along the outer perimeter, enclosing the sacred precinct within a space approximately 6,500 square meters.93 Close by, Hadrian's successor, Antoninus Pius erected a temple to his deified (adoptive) father and likely enclosed it within a large colonnade more than twice as large as the space dedicated to Matidia (Plan 4, No. 4).94Excavations have uncovered fluted columns of giallo antico marble with Corinthian capitals.95

As late as the fourth century C.E., porticoes were still being built in the Campus Martius. A large portico just west of the Baths of Agrippa, and possibly in the vicinity of a temple of Bonus Eventus, may have been constructed in this period. Large Corinthian capitals possibly from the portico were found in the nineteenth century.96 From a fourth-century C.E. inscription, we also learn of a Porticus Maximae that may have followed a street from the Circus Flaminius to the Pons Aelius, now the Ponte Sant’Angelo, a distance of more than 1,000 meters. Columns of granite with marble capitals have been located along its route and may belong to this colonnade of the late empire.97 According to Lanciani, it was possible at this point in time to walk from the imperial fora through the Campus Martius to the Vatican, a distance of more than 3,000 meters, under the cover of colonnades.98

The reasons that the Campus Martius received so many porticoes and Romans enclosed so much area within thousands of meters of column-lined walkways cannot be known with certitude. Nevertheless, we may look to both the topography and the prior and contemporaneous development of the space for answers. The flat and largely undeveloped space within the Field of Mars provided a base on which colonnades could rise without the cost and political issues associated with tearing down existing structures. Aquadriporticus required a large expanse of level ground such as found in the Campus Martius. The colonnades could serve as the defining perimeters of sacred spaces and, with the proliferation of manubial temples in the Campus Martius during and in the wake of the Punic Wars, would add those important lines to religious precincts already constructed or under construction in the field north of the city. Perhaps as importantly, they allowed successful generals laden with the bounty of foreign conquest to apply their manubiaeto another form of architecture that not only faced the triumphal parade route but also served as the repository for the exhibition of captured treasures. The emperors continued this tradition and added to and embellished existing republican colonnades, while also constructing new ones even more resplendent.

As theaters, baths, and pleasure parks attracted an increasing number of visitors to the former marshland, the colonnades served as a marketplace for hawkers of both quotidian and luxury goods that ranged from wigs to inlaid furniture, goblets, and jewelry.99When theatergoers were caught in rainstorms during the open-air performances, porticoes provided fast shelter. To those wandering among the marbled edifices of the imperial Field of Mars, the colonnades could serve as geographic markers and meeting points. Writing in the late first century C.E., the poet Martial humorously described the desperation of one Selius wandering through the Campus Martius in search of someone to take him to dinner so he does not have to eat at home. He begins at the Porticus Europae, which may be the Porticus Vipsania located on the eastern edge of the Field of Mars.100 The hungry Selius next runs to the Saepta Julia and then to the Porticus Argonautarum, but has no success. He doubles back to the nearby Temple of Isis and then heads a few blocks south to the Hecatostylon. Still unable to find anyone willing to take him to a meal, Selius searches among the double row of trees in Pompey's portico. Failing in that effort, he meanders back to the Porticus Vipsania to again try his luck there.101Martial's readers would have understood his reference to the “roof supported by a hundred columns” as the Hecatostylon and recognized “the gift of Pompey and the double wood” as the tree-lined portico behind his great theater.102 These were well-known meeting places and part of the imperial urban fabric.

To get from one colonnade to the next, however, Selius would have been forced to travel by foot. Moreover, he could not have easily found a direct route. By the end of the first century C.E., what had been mostly open space in the central Campus Martius was subdivided into numerous rectangles and semicircles pushed hard up against each other with little maneuverable room for street traffic. The subdivisions were created in large part by the porticoes themselves that enclosed or were attached to the temples, theaters, and parks. Relatively wide streets such as the Via Flaminia bordered the space and forced pedestrians to enter the porticoes and travel their length or cut across the rectangular enclosures to speed their journey. The alternative was an even more circuitous route through narrow streets that wound around the massive marbled structures.

In this configuration, the porticoes, and in particular the quadriporticoes, in the Field of Mars about which we have literary and archaeological evidence performed more often as “way stations” than connective armature (to use MacDonald's terminology), serving as “social structures, made for pausing or resting, an architecture of invitation, of the opportunity to quit, for the moment, the activity of the pavement.”103 There were likely porticoes in the Campus Martius that did function as part of the city's armature, although the architectural evidence is sketchy.104 Perhaps the best example would be the fourth-century C.E. Porticus Maximae that may have connected the Circus Flaminius with the Pons Aelius to the north. While the Theater of Marcellus acted as a significant bottleneck for traffic at the southern end of the campus, the route of the Porticus Maximae linked a major market and parade assembly ground with a bridge across the Tiber. The porticus a Porta Fontinali ad Martis aram that led from the city gate to the Altar of Marsmight be considered another channel for foot traffic although, at least originally, it served as only a ceremonial connector to an isolated religious site. For the most part, however, the porticoes and specifically the quadriporticoes in the central Campus Martius between the Via Flaminia and roads on the western side near the Tiber did serve as resting points for those attempting to negotiate the now crowded and built-up space. Diverted perhaps from their intended destination, visitors to Pompey's portico and similar spaces in the Campus Martius discovered “an ordered world against which the chaotic untidiness of life might be measured.”105

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