The Round Mardakan Fortress is the best-preserved of the Absheron Peninsula's medieval towers and one of the finest examples of Shirvan-Absheron military architecture in Azerbaijan. Built in 1232, it consists of a cylindrical tower about 16 metres high surrounded by a defensive wall with smaller blind towers — the whole thing was recognised by UNESCO as part of a Caspian Sea defensive heritage reserve in 2001.
The tower is open as a small museum, with a display dedicated to the castle architecture of the Absheron Peninsula. The interior is modest but the building itself is the point: the thick stone walls, the corbelled arrow loops, and the defensive entrance arrangement give a genuine sense of medieval fortress engineering. A sign near the entrance marks the architect's inscription, which names both the builder and the Shirvanshah who commissioned the work.