Orhan Mosque and Kulliye (Center): Kulliye, which is constructed by Orhan Bey in between 1339 and 1340, is composed of mosque, theology school, charitable establishment, school, hamam and inn (Emir Inn) structures. It is on the east part of Ulu Mosque, and one of the first samples of Ottoman Kulliye. Orhan Mosque is one of the most important structures of early Ottoman period in Bursa. Twin arches at both sides are one of the most important characteristics of the structure. It was constructed with two rows of bricks and one row of stone. Brick work on its external surface is also very interesting.