This vast compound some thirty-four acres in area, known as the Haram aI-Sharif (Noble Sanctuary), is situated in the Old City of Jerusalem, one of the three holiest cities of Islam (the other two being Mecca and Medina). In the early days of Islam, Muslims turned in prayer toward Jerusalem and not, as later, toward Mecca. The octagonal structure is the Mosque of the Dome of the Rock, built by the caliph Abd aI-Malik between A.D. 688 and 691. It is the earliest Muslim monument surviving. Behind it is the Mosque of al-Aqsa, built by Abd al-Malik's son al-Walid during his caliphate (A.D. 705-715). The prophet Muhammad was transported from Mecca to Jerusalem in mystical flight on a wondrous steed, al-Buraq; he tethered the steed to a wall (extreme right), the outside of which is the Jewish Wailing Wall. From the rock under the dome, the Prophet ascended to heaven. The smaller cupolas and buildings in and around the compound are variously shrines, colleges, monasteries (of mystical brotherhoods), public fountains, and tombs of Muslim saints and scholars.