Sayyid Rukn ad-din commissioned a complex of structures in Yazd including a mosque, library, madrasa and mausoleum, to form the Muasasa Vaqt u Sa'at: the 'Institute of Time and the Hour'. The complex was completed in 1325. Of the numerous structures erected, only the square, domed mausoleum still stands, known locally as the Masjid-i Vaqt u Sa'at.

The interior of the tomb is completely coated with white plaster, profusely decorated with designs painted, stenciled, or in low relief stucco carving. The dome features a central sunburst-type design created by radial foliage; radiating out from the center are large escutcheons of alternating Naskhi and Kufic text. The double layer of squinches within the zone of transition also display Kufic text formed into unusual designs.

Sources:

Arthur Upham Pope, 'The Fourteenth Century', in A Survey of Persian Art ed. Arthur Upham Pope and Phyllis Ackerman. (Tehran: Soroush Press, 1977), 1089-1090.

Donald N. Wilber, The Architecture of Islamic Iran, (New York: Greenwood Press, 1969).