Gonbad-e Qabus tower is a monument in Gonbad-e Qabus, Iran. The Tower in the central part of the city reaches 72 metres (236 ft) (including the height of the platform) making it the tallest pure-brick tower in the world. The baked-brick-built tower is an enormous decagon building with a conic roof, which forms the golden ratio Phi, that equals 1.618. The interiors contain the earliest examples of Muqarnas decorative styles. The decagon with its 3 meter-thick wall, divided into 10 sides, has a diameter of 17 m . The Tower was built on such a scientific and architectural design that at the front of the Tower, at an external circle, one can hear one's echo.
The tower was built in 1006 AD on the orders of the Ziyarid Amir Shams ol-Ma'āli Qabus ibn Wushmgir.It is located 3 km north of the ancient city of Jorjan, from where the Ziyarid dynasty ruled. The tower is over 1000 years old. Even though the inscription does not explicitly refer to the rumor that the tower was built for the tomb for the prince Ziyarid ruler, it is believed that the Sultan's body was put in a glass coffin and was suspended from the ceiling of the tower.
It has been registered a World Heritage Site, in the tower's upcoming 1,000th anniversary. Gonbad-e Qābus or Gonbad-e Kāvus (also transcribed Gonbad-e Ghābus or Gonbad-i Ghāboos) is a city in the province of Golestan in Iran. The city tower was built with bricks representing a special art related to the 4th century (Hegira, or 11th century). This tower which stands on a domed hill with 15 m height is located in the central (principal) park of Gonbad Kavoos city.
Robert Byron, the British travel writer and architectural critic, wrote that it was a photograph of the tower that motivated him to visit Persia. Seeing the tower, he maintained his high opinion of its qualities, writing in The Road to Oxiana, that 'the Gumbad-i-Kambus ranks with the great buildings of the world.'