Üsküdar (üsküˈdär) [key] or Scutari skōˈtərē, urban district, part of İstanbul, Turkey, on the Asian side of the Bosporus. It is a commercial and industrial center. Known as Chrysopolis in ancient times, it enjoyed its greatest prosperity after the Ottoman conquest (15th cent.). As the gateway to Constantinople (İstanbul), it was embellished with many mosques, caravansaries, and other public buildings. During the Crimean War, Üsküdar was a base (1854–56) of the British army and the site of the military hospital made famous by the work of Florence Nightingale.