Constantinople (historic Byzantium, called Istanbul since 1930) was the capital of the Ottoman Empire and then of Turkey until the seat of government moved to Ankara in the late-1920s. From the seventeenth century until around 1930, the British embassy was at Pera (A), an aristocratic suburb on the north side of the Golden Horn, and the British consulate was at Galata (B), a commercial district on the waterfront south of Pera. The embassy’s summer residence was at Tarabya (C), formerly spelled Therapia, on the Bosphorus from about 1800 until 1911. The consulate-general now occupies the former embassy building at Pera. (The buildings at Pera and Tarabya are described in more detail in Room for Diplomacy.)
Izmir (formerly called Smyrna) was, and remains, the largest consulate in Turkey, established and staffed by the Levant Company until taken over by the British government in 1825.