Büyük Selimiye Mosque (Turkish: Büyük Selimiye Camii), often known simply as Selimiye Mosque, is situated in the district of Üsküdar in İstanbul, Turkey, right across the Selimiye Barracks. The mosque was commissioned by Ottoman Sultan Selim III (reigned 1789-1807) and completed in 1801, however its main architect is unknown.
Büyük Selimiye Mosque has a western style, a wide courtyard and four entrance doors. After the completion of the mosque, the original minarets were thought to be too thick, and later shaved. The mosque is seen as a masterpiece of carpentry and marble work. The dome is 14.6 m (48 ft) wide, has five windows and supported by four half domes. Büyük Selimiye Mosque has a "muvakkithane" for keeping prayer times and a water fountain.