Byzantium was a Greek city located on the western side of the Bosporus, one of the straits* that separates Europe from Asia Minor. The city had great strategic importance because it was situated on a hilly, triangular-shaped peninsula and had natural protection against attack. Its large, well-protected natural harbor, known as the Golden Horn, provided a secure location for ships. Its location at the crossroads of Europe and Asia made the city an important center of trade. In late Roman times, Byzantium became the capital of the Eastern Roman Empire (later known as the Byzantine Empire) and the name of the city was changed to Constantinople.

Byzantium was founded in the 600s B.C. by Greeks from the city of Megara. According to tradition, it was named after its legendary founder, Byzas. Before setting sail from Megara, Byzas asked an oracle where he should establish a new colony. The oracle replied, “Opposite the blind.” When Byzas reached the Bosporus, he found another Greek city already in place on the opposite side of the strait. It was called Chalcedon (which means “city of the blind” in Greek) because its founders had failed to take advantage of the better location on the western side of the strait, the site chosen by Byzas.

Soon after its founding, Byzantium flourished as a center of trade. Its principal products included fish, grain, furs, honey, gold, and wax, much of which came from areas around the Black Sea. In 512 B.C., the Persian king, Darius I, conquered Byzantium. It remained part of the Persian Empireuntil 478 B.C., when the Greeks, under the leadership of Pausanias of Sparta, liberated the city. The next year, Athenians forced out the Spartans, and Byzantium became a member of the Delian League, an alliance of city-states* headed by Athens. The Athenians and Spartans competed for control of the city for almost 150 years.

In the mid-300s B.C., the people of Byzantium successfully resisted an attempt by Philip II of Macedonia to seize control of the city. However, they were unable to resist Philip’s son, Alexander the Great. When Alexander asserted his control over Greece in 335 B.C., Byzantium acknowledged Macedonian rule. Even so, the city continued to enjoy considerable freedom.

Byzantium formed an alliance with the Romans in 146 B.C. and gradually lost its independence in the years that followed. The emperor Septimius Severus destroyed the city in A.D. 196 because its inhabitants had supported his rival during a period of civil war. He later rebuilt the city because of its strategic importance and renamed it Augusta Antonina. In A.D. 330, the emperor Constantine I chose Byzantium as the new capital of the empire and changed its name to Nova Roma, or “New Rome.” Soon, however, the city became known as Constantinople, and it remained the most important city of the Eastern Roman Empire. (See also Rome, History of; Greece, History of.)

* strait narrow channel that connects two bodies of water

* city-state independent state consisting of a city and its surrounding territory

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