The 12th-century green dome, immortalised by a reference to it in the poet Khaqani's work, has long since been removed, but the untopped brick tower remains famous for the whirling floral stucco added in the Ilkhanid Mongol era; this ornamentation is described by an enraptured Robert Byron in Road to Oxiana. In the crypt (steps down from the rear interior) is the plain-blue-tiled Alaviyan family tomb, covered with votive Islamic embroidery.