Guldursun Fortress, Southern Karakalpakstan

Major Guldursun lies about seven kilometres east of Buston among cultivated fields and farmsteads. West of the ancient Tazabagyab channel stand the remains of Minor Guldursun, a medieval palace protected by towers and fortified walls.

Major Guldursun, measuring approximately 350 by 230 metres, is one of the largest fortresses of ancient Khorezm and almost twice the area of Major Kyrk Kyz Kala. Its foundations contain fortification elements dating from the 4th–3rd centuries BC through the 4th century AD. The walls and towers visible today were built by the Khorezmshahs in the 12th century over the abandoned ancient fortress.

Mongol forces captured Guldursun in 1220, although the fortress was not completely destroyed. Almost the entire wall circuit survives, in places reaching approximately 15 metres. The only entrance is on the eastern side and is protected by a gate labyrinth. A separate defensive wall runs about 18 metres outside the main circuit; its towers may once have been connected to the fortress by bridges.