The settlement history and urban development of Pergamon are characterized by several phases of expansion, but also decline of the city, which repeatedly changed its character over time. After a history of about 250 years as a fortified Hellenistic residential city, Pergamon did not fundamentally change its face until the Roman Imperial period. In the course of the 1st century, Pergamon increasingly expanded beyond the city fortifications on the alluvial fan of the Selinus river