Ephesus, Turkey is located in the Asian portion of Turkey. It was an ancient Greek city that was later taken over by the Romans. During the 1st century AD the city was one of the largest in the Roman Empire and very prosperous. In ancient times it was located on the Cayster River which provided port access to the Agean Sea. However, over the course of time the river changed course, just as did the river near the ancient site of Ostica Antica in Italy. Then the harbor silted up and the town was virtually abandoned. This, among with other historical events let to the downfall of Ephesus.