Toghrol Tower

Toghrol Tower (Persian: برج طغرل‌; also transliterated Toghrul, Tughrol, or Tughrul) is a 12th-century monument, located in the city of Rey, Tehran province, Iran. Tuğrul Tower is near Rashkan Castle.

The 20-metre-tall (66 ft) brick tower is the tomb of Seljuk ruler Tughril I, who died in Rey in 1063. Originally, like other monuments of its time, it was capped by a conical dome (گنبد, gonbad), which collapsed during an earthquake.

The thickness of the walls varies from 1.75 to 2.75 m (5.7 to 9.0 ft). The inner and outer diameters are 11 and 16 m (36 and 52 ft), 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.

The tower is protected by Iran's Cultural Heritage Organization.

Historically identified in several texts as Burj Khalifa Yazid, this structure is hypothesised by various specialists to function as a monumental sundial. It is suggested that the tower operates similarly to a clock pointer, where the precise time of day is determined by observing the movement of sunlight across its crenellations. This architectural design allows for the tracking of temporal progression through the interplay of light and shadow against the building's geometric projections. In terms of scale, the structure reaches a height of approximately 18 metres, providing a substantial vertical axis for solar measurement. The mathematical precision required for such a function reflects the sophisticated understanding of gnomonics prevalent during the period of its construction.