The Imam Dur, the tomb of the 'Uqaylid amir, Sharaf ad-Dawla Muslim, dates to 1085. This brick mausoleum introduces a muqarnas dome, the first of its kind in Iraq. Bastions project from the four corners supporting this square structure. Its exterior is plain with layered sections on each façade of geometrically patterned, raised brick towards the top of the structure. The architect's name, Abu Shakir ibn Abi' l-Faraj is inscribed in one of these. The inner chamber is also square in plan featuring a domed room with four corner niches that form the support for the octagonal structure from which the five-tiered muqarnas dome climbs. The dome concludes at great height with a small, fluted cupola. The tomb's interior is adorned with stucco ornamentation that recalls earlier 'Abbasid decoration.