The Round Mardakan Fortress or the Small Mardakan Castle is a historical and architectural monument located in the Mardakan settlement of the Khazar district in Baku. By the Decree of the Cabinet of Ministers of the Republic of Azerbaijan, it was included in the list of historical and cultural monuments of world importance. In 2001, together with other coastal defence facilities of the Caspian Sea, it was included in the UNESCO World Heritage Reserve List.

Mərdəkan (Mardakan) is a settlement and municipality in Khazar raion of Baku, Azerbaijan with a population of 25,232. It's located on the eastern Absheron Peninsula only 30 km away from capital city Baku, bounded by the Caspian Sea to the north, Shuvalan to the east, Qala to the south, and Shagan to the west. Mardakan received the status of a settlement in 1936. In 1933, Shagan village was included in the Mardakan village council, although it was separated in 1945, it was reunited in 1948, and in 1990, Shagan re-separated and received the status of a settlement.