Both al-Hasan ibn Kay Khusrow (d. 1318) and his daughter (d.1307) lie buried in this square mud brick tomb located near the Friday Mosque. Structures made almost entirely of mud brick such as this are now rare; the material has not held up over time, as evidenced at this site: the northern corner from the ground to the zone of transition has collapsed. Use was not made of a reinforcing layer of fired brick, as commonly found elsewhere. Here, fired brick is limited to the eight arches in the zone of transition.
The interior is coated with hard white plaster upon which decorative bands, mouldings and panels have been painted or stenciled. The zone of transition is unusual: smaller arches were constructed within the structural corner arches; the latter plastered and indicated by a painted line, the former filled with decorative muqarnas.
Donald N. Wilber, The Architecture of Islamic Iran, (New York: Greenwood Press, 1969) p.154