The Ahırkap Feneri, a historical lighthouse still in use, is located at the southern Seraglio Point on the Rumelian coast of Bosporus' south entrance, in Ahırkapı neighborhood of Istanbul's Fatih district, Turkey. It is across from the Kadıköy İnciburnu Feneri, which is on the Anatolian coast of the strait at a distance of 1.5 nmi (2.8 km). A line connecting the two lighthouses marks the southern boundary of the Port of Istanbul.
In 1857, Sultan Abdülmecid I (reigned 1839-1861) commissioned the building of a lighthouse, which was constructed by French engineers in Ahırkapı (literally English: Stable Gate) right outside of the city walls south of the Topkapı Palace. The masonry lighthouse has a conical shape and is painted white with one narrow black horizontal band. To the 26 m (85 ft) high tower, a keeper's house is attached.
Initially, the lighthouse was lit by kerosene, however the light source was later replaced by Dalén light using carbide (acetylene gas). Finally, it was electrified. The lighthouse's lantern has a 500mm catadioptric cylindrical lens and a 1,000 W lamp. At a focal height of 36 m (118 ft), it flashes white every 6 seconds, which is visible at a range of 16 nmi (30 km) in the Sea of Marmara. Ahırkapı Feneri is listed in Turkey under the code "TUR-056" and its radio call sign is TC1ALH. It is operated and maintained by the Coastal Safety Authority (Turkish: Kıyı Emniyeti Genel Müdürlüğü) of the Ministry of Transport and Communication.