The Osman Shah Mosque — also known as the Kursum Mosque (from the Turkish word for "leaden", referring to its lead-covered dome) — is a former Ottoman mosque from the sixteenth century, one of the best-preserved examples of Ottoman religious architecture in Thessaly. It was built during the reign of Suleiman the Magnificent and named after a local Ottoman administrator. The dome and minaret survive largely intact.
After the Greek reconquest of the region in 1881, the mosque lost its religious function and has been used variously as a warehouse, prison, and archaeological storage. It's not always open to visitors, but the exterior — a handsome domed structure with decorative stonework — is worth seeing from the street. It stands near the main square, a visible reminder of Trikala's four centuries under Ottoman administration.