The 20 meters tall brick tower is the tomb of Seljuk ruler Tuğrul Beg, who died in Rey in 1063. Originally, like other monuments of its time, it was capped by a conical dome ( gonbad), which would have added to its height. The dome collapsed during an earthquake.
The thickness of the walls varies from 1.75 to 2.75 meters. The inner and outer diameters are 11 and 16 meters, respectively. The exterior shape is that of a polygon with 24 angles in its design, which is thought to contribute to the structure’s stability against tremors.
At the top of the tower Kufic inscriptions were originally observable. Naser al-Din Shah ordered some restorations to be made to the top part of the tower, which was collapsing in 1884.
The tower is protected by Iran’s Cultural Heritage Organization.