The Mausoleum of Sultan Olje?tu at Sultaniyya (1307-13). Intended as a major component of a larger complex, this octagonal structure with eight slender minarets and a huge, blue-glazed dome is not well understood. Olje?tu had the idea of transforming it into a mashhad for Ali and his son al-Husayn when he converted to Shiism but then changed his mind again and made it his own, and plastered the interior. The building shows the striving for verticality and the perfection of pre-existing traditions.