The Umayyad Mosque, also known as the Great Mosque of Damascus located in the old city of Damascus, is one of the largest and oldest mosques in the world. The earliest surviving stone mosque, built between AD 705 and 715 by the Umayyad Caliph al-Walīd I. The ground plan of the Umayyad Mosque is rectangular in shape and measures 97 meters by 156 meters. A large courtyard occupies the northern part of the mosque complex, while the sanctuary covers the southern part. The courtyard is enclosed by four exterior walls. Arcades (riwaq) surround the courtyard supported by alternating stone columns and piers. There is one pier in between every two columns. Three arcades make up the interior space of the sanctuary. .