Constructed between 1339 and 1340 by Orhan Gazi, this is one of the most important early Ottoman constructions in Bursa. Pointed arches on the veranda show the beginnings of a particularly Ottoman detail, while the exterior brickwork recalls its Selçuk origins. The mosque was damaged in 1413 by Karamanoglu Mehmet Bey and repaired in 1417 by Çelebi Sultan Mehmet. Note the star-shaped decorations representing the course of the sun and the marble embellishments on the eastern and western facades.

The surrounding complex is one of the first in the Ottoman tradition, consisting of a mosque, medrese, soup kitchen, bath, and inn. The cats apparently stay there free of charge, and the whole courtyard and mosque interior have a homey feel.