Also known as: Mil-e Radkan Chenaran, Raadkan Tower

Radkan tower (Mil Radkan Chenaran) is located in 26 kilometers northwest of Chenaran city, Razavi Khorasan province. This conical tower with height of 25 meters’ dates back to 13th century during Mongols invasions. Mil-e Radkan was a structure which helped residents determine the beginning of the four seasons, leap years and Nowruz.

The structure seems to have been completed in 1261 AD. Shape of the tower is like a cone. Internal diameter of tower is 14 and external diameter is 20 meters. The tower has dodecagon walls which are precisely constructed.

During 12th century, it was the first tower demonstrating the seasons and new year. Here was designed by Nasir ad-Din al-Tusi. The doors of the tower have set the base on situation of sunrise and it was the way to show the seasons. The tower also was used for astronomy. Date of construction, descriptions and some texts about designer are carved at the top of it on the stone. Materials used for building the tower are brick, lime, plaster and clay.