Round Tower (Mardakan) built
1232 CE.
Shown on the map at 40.496°, 50.147°.
The Round Mardakan Fortress or the Small Mardakan Castle (Azerbaijani: Dairəvi Mərdəkan qalası, or Kiçik Mərdəkan qəsri; Persian: قلعه گرد مردکان, or قلعه کوچک مردکان) 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. The inscription (kitabe) on the castle's donjon says that it was built in 1232 by the architect Iranian Abdulmajid ibn Masud at the order of the Iranian Shirvanshah Fariburz III. During the construction of the castle, lime mortar and local limestone were used. The Round Mardakan castle on plan consists of a central tower surrounded by powerful walls of 7 meters high supported by blind towers on the sides. The diameter of the tower is 7.6 m, the thickness of the walls on the lower floor is 2 m. Inside, the tower is divided into three tiers covered with stone flat domes.
Text from the Wikipedia article Round Mardakan Fortress, licensed CC BY-SA 4.0.