The Haji Özbek Mosque (1333) in Iznik, which was the first important centre of Ottoman art, is a prime example of Ottoman single-domed mosque, which illustrates a combination of Byzantine building techniques and Muslim needs.[1] According to the inscriptive plaque (kitabe) above a window, the mosque was built by Haci Özbek bin Muhammed in the year 1333 (734 A.H.), two years after the Ottoman conquest of Iznik by the Ottoman sultan Orhan I.[2] The building is a single-unit mosque composed of a square hall crowned with a dome, which is eight metres (26 ft) in diameter. The drum of the dome of the mosque is dodecagonal and adorned with a band of triangular planes on the interior. The mosque consists of a triple layer of brick with alternating layers of individually cut stone separated by vertically laid brick.[3]