The citadel (Iş Kale) is 200 times 80 meters, and was built by the Byzantines in the sixth century. Its present outlay is mainly the result of Seljuk additions and changes. The building times of some towers is known, i.e. the Yoğun Burç or Fat Tower (1212) and the Hassan Bece Burç. There is a mosque within the citadel, founded by Mehmet II in 1468.
Nowadays its a shopping area with a special atmosphere.