Rumeli Fortress Rumeli Castle is a fortress situated on the shores of the Bosphorus Strait. Ottoman sultan Mehmed II, famously known as "Mehmed the Conqueror," built it in 1452 as part of his plan to invade Constantinople. It's located across from another Ottoman castle, Anadolu Castle, constructed in 1394 by Bayezid I, both intended to prevent military and economic aid from reaching Byzantium via the Black Sea. The fortress consists of three large towers, one small tower, and thirteen smaller towers, all of which remain in excellent condition. After the fall of Constantinople, Rumeli Castle served as a customs checkpoint, controlling the passage of ships through the strait. However, its strategic importance waned when fortresses were built further up the Bosphorus, at the meeting point with the Black Sea. During the 17th century, Rumeli Castle became a prison primarily for foreigners captured in war. It suffered partial destruction in 1509 due to an earthquake but was soon repaired. Sultan Selim III (1761-1807) rebuilt and restored the fortress, which served as a residential neighborhood during the 19th century. However, it fell out of use in the 19th century.