Now, Cyzicus is protected by the Turkey's Ministry of Culture, and located on the Erdek and Bandırma roads in Turkey.
Owing to its advantageous position it speedily acquired commercial importance, and the gold staters of Cyzicus were a staple currency in the ancient world till they were superseded by those of Philip of Macedon. Its unique and characteristic coin, the Cyzicenus, was worth 28 drachmae. During the Peloponnesian War (431-404 BC) Cyzicus was subject to the Athenians and Lacedaemonians alternately. In the naval Battle of Cyzicus in 410 during the Peloponnesian War, an Athenian fleet routed and completely destroyed a Spartan fleet. At the peace of Antalcidas (387 BC), like the other Greek cities in Asia, it was made over to Persia. Alexander the Great later captured it from the Persians in 334 BC.
The history of the town in Hellenistic times is closely connected with that of the Attalids of Pergamon, with whose extinction it came into direct relations with Rome. Cyzicus was held for the Romans against king Mithridates VI of Pontus who besieged it with 300,000 men in 74 BC, but it withstood him stoutly, and the siege was raised by Lucullus: the loyalty of the city was rewarded by an extension of territory and other privileges. The Romans favoured it and recognized its municipal independence. Cyzicus was the leading city of Northern Mysia as far as Troas.
Under Roman Emperor Tiberius it was incorporated with the empire, but remained the capital of Mysia, afterwards of Hellespontus, and became one of the greatest cities in the ancient world.
Cyzicus was captured temporarily by the Arabs in 675. It appears to have been ruined by a series of earthquakes since 443 — the last in AD 1063; it began to be deserted as early as the eleventh century and the population was transferred to Artaki at least as early as the 13th century, when the peninsula was occupied by the Crusades.
In the Ottoman era it was part of the caza of Erdek, in the Anatolian vilayet of Brusa.
Cyzicus is still a metropolitan title for the Greek Orthodox, the metropolitan residing at Artake (Erdek), a little port on the western shore of the peninsula. Opposite to Artake is another port, Peramos (Perama), where an Assumptionist Father founded a Greek parish. At Panormos (Panderma), another more important port nine miles south-east of the ruins of Cyzicus (10,000 inhabitants), there is a Catholic Armenian parish. At the Dardanelles there is also a Latin parish. It remains a Catholic titular see.
The picturesque amphitheatre, intersected by a stream, built in the third century B.C., was one of the largest in the world; its diameter was nearly 500 feet. Of this magnificent building, sometimes ranked among the seven wonders of the ancient world, thirty-one immense columns still stood erect in 1444. These have since been carried away piecemeal for building purposes.
Colossal foundations of a temple dedicated to the Emperor Hadrian are still visible: the columns were 21.35 metres high (about 70 feet), while the highest known elsewhere, those at Baalbek in Syria are only 19.35 metres (about 63 feet).
The monuments of Cyzicus were used by the Byzantine emperor Justinian as a quarry for the building of his Saint Sophia cathedral, and were still exploited by the Ottomans.