Round Tower, Medieval fortress in Mardakan, Azerbaijan.

The Round Tower is a 1232 fortress in Mardakan consisting of a central cylindrical donjon 15 m high and 7.6 m in external diameter, with 2 m thick walls, enclosed by 7 m high walls 25 m long on each side, reinforced by blind corner towers. Inside, three tiers are covered by flat stone domes with circular openings at their centres. The ground-level entrance leads to a first floor with no other openings; the second-floor entrance sits over 3 m above the first-floor level.

The tower's kufic inscription states it was built in 1232 by the architect Abdulmajid ibn Masud on the order of Shirvanshah Fariburz III. It formed part of a larger fortress complex on this site that has not survived. In 2001 it was placed on the UNESCO World Heritage tentative list with other Caspian coastal defences, and restoration ran from September 2025 to January 2026.

The tower's name comes from its round plan, and locals also call it the Small Mardakan Castle. The geometric carved ornament on the lowest bracket course is a detail to look for on the exterior. The upper platform, now lost its parapet, was the main defensive position.

Restoration work runs from September 2025 to January 2026, so the interior may be closed; check access before travelling. The tower stands in Mardakan, Khazar district, Baku. The only entrance is at ground level, while the second floor is reached from more than 3 m above the first-floor level.

The raised entrance was a deliberate defensive strategy that made it harder for attackers to breach the fortress quickly. Narrow loopholes in the walls reveal how archers could monitor the surroundings while remaining protected from outside threats.