Sarajevo was founded by the Ottoman Empire in the 1450s upon its conquest of the region, with 1461 used as the city's founding date. The first Ottoman governor of Bosnia, Isa-Beg Ishaković, transformed the cluster of villages into a city and state capital by building a number of key structures, including a mosque, a closed marketplace, a public bath, a hostel, and of course the governor's castle ("Saray") which gave the city its present name. The mosque was named "Careva Džamija" (the Emperor's Mosque) in honor of Sultan Mehmed II. With the improvements, Sarajevo quickly grew into the largest city in the region. By the 15th century the settlement was established as a city, named ''Bosna-Saraj'', around the citadel in 1461.