Constructed on the site of the Second Jewish Temple, which was destroyed during the Roman Siege of Jerusalem in 70 CE. In 637 CE, Jerusalem surrendered to the Rashidun Caliphate army during the Muslim conquest of Syria. The structure has been refurbished many times since its initial completion in 691 CE at the order of Umayyad Caliph Abd al-Malik. The site's significance stems from religious traditions regarding the rock, known as the Foundation Stone, at its heart. Consisting of a domed octagon over the rock and a double ambulatory some 12 m wide, the building is a centralized structure of a type long familiar in Roman mausolea and Christian martyria. The choice of form probably stems from a desire to upstage the nearby domed church of the Holy Sepulchre, also built over a rock. It is richly decorated with tile and Koranic inscriptions.