Jerusalem.
Jerusalem became known as Al-Quds, The Holy. Many of the Prophet's Companions travelled to worship at the blessed spot to which Muhammad, peace and blessings be upon him, was brought by night and from which he ascended through the heavens to his Lord. According to the authenticated tradition of the Prophet, travel for the sake of worship is undertaken to only three mosques; the Sacred Mosque in Makkah, the Prophet's Mosque in Madinah, and the Furthest Mosque in Jerusalem. In 685AD the Umayyad Khalif, 'Abdul Malik ibn Marwan, commenced work on the Dome of the Rock. Essentially unchanged for more than thirteen centuries, the Dome of the Rock remains one of the world's most beautiful and enduring architectural treasures.