The Beylerbeyi Mosque (Turkish: Beylerbeyi Camii), also known as the Hamid i-Evvel Mosque (Turkish: Hamid-i Evvel Camii), is a mosque located in the Beylerbeyi neighbourhood in Istanbul, Turkey. It was first built in 1777–1778 by the Ottoman sultan Abdülhamid I, but was later modified by Mahmud II in 1820–1821.