The Il-Arslan Mausoleum, built on the grave one of the best known khorezmshah Il-Arslan, is the most ancient surviving buildings of Urgench, the capital of Khoresm.
Taj ad-Din Il-Arslan was khorezmshah and descend from Bekdilli tribe. He ruled from 1156 to 1172. He mounted the throne in Khoresm after the death of his father khorezmshah Ala ad-Din Atsyz. In the 1160-ies Il-Arslan added Dekhistan with its suburbs to Khoresm. In 1172 the troops of khorezmshah successfully repelled an attack of the Qara khytais to Khoresm. Not long after the ruler died, the memory of him was perpetuated after building of the mausoleum in the second half of XII century, noted, first of all, for its magnificent decoration of main fascade.
The mausoleum presents a cube, on which the twelve-sided prism of drum and dome in a form of the twelve-sided tent were raised. There are no any similar buildings in the Central Asia. A square structure is in the cardinal directions. The main fascade is directed to East. Total height of the mausoleum premises twice as much as height of its walls.
The building is one of the first in the Central Asia, which height was artificially increased using the space between the internal dome and external tent. This novelty, which shapes the structure like obelisk, was realized later in many grandiose structures of Tamerlane and his posterity.
One more unique peculiarity of the mausoleum is the hand-made decoration of building by the relief carved terracotta, arranged in the unusual ornament, consisting of the plant и and geometric patterns. The original application process was used at that. The closely placed on ground raw bricks were covered with clay, on which the complicated ornament was made. Then all composition was cut along joints between bricks and together with them was burnt, after which it was arranged again but now on the fascade.
At present the Il-Arslan mausoleum, along with other architectural marvels of Kunyaurgench, is amongst the best-known sightseeing of Turkmenistan.