Turabeg Khanum was the daughter of Uzbek Khan, under whose rule the Golden Horde converted to Islam, and the wife of Gutlug Timur, a governor of Urgench in the early 14th century. The Mausoleum of Turabeg Khanum has an imposing southfacing portal, some 25m high. Behind this is a domed lobby, with a spiral staircase (locked to visitors) to the right. The main chamber beyond is hexagonal in plan, with tall arched niches on each wall. The mosaic on the underside of the dome is stunning, its design apparently involving 365 interlocking geometric figures, one for each day of the year.