Ulugbek Madrasah was built between 1417 and 1420. Its huge portal has a 15 meter arch. A mosaic panel above the arch shows the symbolical sky with five and ten-pointed stars. The madrasah had a platform for astronomical observations made before Ulugbek's observatory. Madrasah had fifty cells for one hundred students. Sheikh Khodja Akhrar and poet Djami were among outstanding graduates of the madrasah. In the 20th century the northeastern and southeastern minarets were repaired, new domes installed, the portal arch and tympana restored.