The Ulu Cami (Great Mosque) is Mardin's principal congregational mosque, built in the 12th century during the Artukid period on the site of an earlier church. The mosque is distinguished by its tall minaret — a cylindrical tower with a conical cap, a hallmark of Artukid architecture — and the interior, though austere, has clean proportions and some notable carved stonework around the mihrab (prayer niche).
The mosque is active and open to non-Muslim visitors outside prayer times (cover appropriately and remove shoes). The surrounding streets in this part of the old city are particularly well-preserved and give a good sense of medieval urban fabric: narrow lanes between high stone walls, occasional glimpses into carved courtyards, and the play of light and shadow that is one of the particular pleasures of Mardin's architecture.