Ulu Cami - the largest mosque in Bursa and a landmark of early Ottoman architecture which used many elements from the Seljuk architecture. Ordered by Sultan Bayezid I, the mosque was designed and built by architect Ali Neccar in 1396?1400. It is a large rectangular building, with twenty domes arranged in four rows of five that are supported by twelve columns. Supposedly the twenty domes were built instead of the twenty separate mosques which Sultan Bayezid I had promised for winning the Battle of Nicopolis in 1396. The mosque has two minarets. There is also a fountain (sadirvan) inside the mosque where worshipers can perform ritual ablutions before prayer. Inside the mosque there are 192 monumental wall inscriptions written by the famous Ottoman calligraphers of that period.