The Mamluk Sultan of Egypt and founder of the Qalun dynasty, which ruled Egypt for about a hundred years. After Baybars became the Sultan of Egypt and Syria in 1260, Qalaun also became powerful as his assistant. When Baybar died in 1277, he deposed Baybar's sons and himself became Sultan in 1279. He ruled Egypt from 1279 to 1290, defeated the Mongols in 1281 at the Battle of Homs and In 1289 he captured Tripoli which was the largest town still held by the crusaders. Qalaun built Maristan a large hospital in Cairo and also the famous Masjid-e-Qalun in 1283-85 with a madrassa (college) attached to it along with residential quarters for the students. Round horse shoe arches were used first time for this hospital- mosque-college complex. Qalaun died during a siege of the town of Acre, which his son Khalil captured from the crusaders in 1291.