Kyzikos

This was a Hellenistic city from around 800 BC, when Kapıdağ was still an island in the region of Mysia. Cyzicus became an important port from 400 BC controlling Marmara sea traffic. It was held by Alexander the Great from 334 BC and then by the Romans, but fell into ruin from around 443 AD - perhaps a combination of earthquakes, silting of the port, and economic eclipse. Its masonry and monuments were enthusiastically looted, many finding their way to the kilns to be recycled as lime until an enlightened district governor stopped the operations in the late 1940s, but you can still see the city walls, the foundations of a temple to Hadrian, and the amphitheatre at the far side of the site.