The Radkan Tower,
A highly sophisticated instrument for studying the stars, located in Khorasan Razavi Province 80 kilometers from Mashhad and on the road to Chenaran in the old Radkan City.
This conically spired 25m brick tower has baffled visitors for centuries. On the morning of the first day of winter, at sunrise, the sunlight enters directly from the back door of the Radkan tower and goes out of the front door. Tower divided to 12 outer brick wall, 30 degrees, and 12 sections. Each wall covers 30 degrees angle from the horizon. Choose the place of windows and doors of the tower was not accidental; doors were built in the zone “Yadldaee” dawn (winter) and the beginning of summer sunset.
The largest sun protractor of the world, approximately800 years old, is the masterpiece of Khajeh Nasir-E-Toosi, 70 km north of Mashhad. It has the following applications:
1- Determine the beginning of the 4 seasons
2- Determine the exact date of the Nowruz even the leap-year
3- Determine the Azan of noon
4- Identification of the polar star
5- A giant solar calendar
Radkan has many features and is pride source for Iranian; thus, we highly recommend to pay a visit to the glory and grandeur of ancient Iranian architecture combined with accurate calculations of mathematics and astronomy; the Radkan tower.