Eight freestanding gates are located at the top the staircases leading to the platform of the Dome of the Rock on Temple Mount. Each gate consists of arched entranceways supported by 2-4 columns that are set between two pilasters. Such gates are known in the Roman architecture of monumental entranceways (propylea), which led to temple enclosures. The early Arab geographers mention the gates, but their exact date of construction is not clear. The earliest evidence for their existence is an inscription on one of the columns of the western entranceway, which mentions the name of Abu Bakr from the time of the Abbasid caliph al-Mutia (951 CE). The other gates were built later in the Middle Ages, probably to replace earlier ones that were built in the Umayyad period.