Hazreti Süleyman Camii, also called Kale Camii (Citadel Mosque) is a small mosque within the citadel of the old walled city of Diyarbakır. An inscription on the mosque's minaret dates it to 1160. Its position just outside the citadel's inner Artuqid walls suggests that it was constructed before these were built. 

The mosque sits on a steeply sloping site, higher at the west end than the east. It consists of a rectangular prayer hall, adjoined on its west side by a cuboid building with a pitched roof and on its northeastern side by a tall minaret. An irregularly shaped forecourt adjoins this complex to the west and north. 

The forecourt is bounded on the south and west by a thin, straight wall, and on the north by the Artukid citadel walls, from which projects a large semicircular tower into the space of the forecourt. Visitors reach the forecourt through flights of stairs on the west or south sides.

The prayer hall is oriented north-south and divided into three bays by two sets of piers running east-west. The southern (qibla) and central bay are barrel vaulted. The pavilion like building to the west is known as Sahabeler Türbesi, referring to the sahaba or companions of the prophet. 

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