Kilyos, also Kumköy, is a village located in the Sarıyer district of Istanbul, Turkey. It is also a well-known seaside resort on the Black Sea coast of the European side of Istanbul Province, famous for its beaches.
There is a 14th-century Genoese castle in the village, which was restored during the era of the Ottoman sultan Mahmud II, but it is not publicly accessible since it is located in the military zone. A historical cistern, eight cannons, and a 26-meter-high monumental plane tree are also spectacular within the castle area.
Coordinates: 41°14′57″N 29°02′15″E / 41.24917°N 29.03750°E