Iznik is a small town in northwestern Turkey, on the eastern shore of Lake Iznik. It is the modern successor of the important Byzantine city of Nicea (or Nicaea), where the famous Council of Nicea was held in 325 AD.
Several monuments from the Roman, Byzantine and Ottoman ages are well preserved in modern Iznik. Nicea's Roman and Byzantine city walls, 14,520 feet (4,426 m) in circumference, remain almost entirely intact around the city. They were built in 300 BC by the Greek Lysimachus, then ruler of the town, and were frequently repaired by the Byzantines and Ottomans. The main gate is the Istanbul Gate, on the north side, decorated with a carved relief of fighting horsemen.
Nicea had an ancient theater, built between the lake and Yenisehir Gate. It was built by the Proconsul of Bythinia, Plinius, in 112. By the 13th century, it was turned into a mass grave. Archaeological excavations have revealed that a church, palace, Ottoman ceramic workshops and tile kilns were constructed within it.
The First Council of Nicea was held in the Senatus Palace, which sadly now lies beneath the waters of Lake Iznik. The highlight for religious travelers and historians are the ruins of the 4th-century St. Sophia Cathedral, the site of the Second Council of Nicea. It is located in the town center. Renamed Orhan Ghazi Mosque in 1331 and badly damaged by earthquake and fire, the building was restored by the famous architect
Sinan in the 16th century. The ceiling of Haghia Sophia has collapsed but much still remains. On the wall of a grave room is a fresco of Christ and there are surviving mosaic pavements on the floor. The 14th-century Green Mosque (Yesil Camii) is named for the green tiles adorning its minaret. The original tiles have now been replaced by inferior copies. The Iznik Archaeological Museum is across from the mosque. One of Iznik's nicest historical buildings, the museum is housed in the Kitchen of Lady Nilüfer (Nilüfer Hatun Imareti). The imaret (kitchen) was set up in 1388 by the wife of Ottoman ruler Orhan Gazi, as a hospice for wandering dervishes. Visitors enter through a spacious five-domed portico, which leads to a central domed area flanked by two more domed rooms. The museum's collection consists mainly of Roman antiquities and glass, supplemented with some recently-discovered Seljuk and Ottoman tiles.