Iznik aka Nicaea

İznik (which derives from the former Greek name Νίκαια, Nicaea) is a city in Turkey which is known primarily as the site of the First and Second Councils of Nicaea, the first and seventh Ecumenical councils in the early history of the Christian church, the Nicene Creed, and as the capital city of the Empire of Nicaea. It served as the interim capital city of the Byzantine Empire between 1204 and 1261, following the Fourth Crusade in 1204, until the recapture of Constantinople by the Byzantines in 1261.

The city lies in a fertile basin at the eastern end of Lake Iznik, bounded by ranges of hills to the north and south. It is situated with its west wall rising from the lake itself, providing both protection from siege from that direction, as well as a source of supplies which would be difficult to cut off. The lake is large enough that it cannot be blockaded from the land easily, and the city was large enough to make any attempt to reach the harbour from shore-based siege weapons very difficult.

The city is surrounded on all sides by 5 km (3 mi) of walls about 10 m high.