The Fortress of Anatolia (Turkish “Anadolu Hisarı”) is located near the narrowest point of the Bosphorus by the Göksu stream. It was built by Sultan Beyazit I Yıldırım (the “Thunderbolt”) around 1390, probably partly in preparation for his failed siege of Constantinople in 1394. It is possible that its barbican and keep were added by Mehmet II when he built the Rumeli Hisarı in 1452. Its original name was Güzelce Hisar (“Beautiful Castle”).