|The Umayyad Mosque, also known as the Grand Mosque of Damascus, located in the old city of Damascus, is one of the largest and oldest mosques in the world. It is considered the fourth holiest place in Islam. After the Arab conquest of Damascus, the mosque was built on the Christian basilica dedicated to John the Baptist since the time of the Roman emperor Constantine I. The mosque holds a shrine which still today contains the head of John the Baptist (Yahya), honored as a prophet by both Christians and Muslims alike. There are also many important landmarks within the mosque for the Shiitah, among them is the place where the head of Husayn (the grandson of Muhammad) was kept on display by Yazīd I. There is also the tomb of Saladin, which stands in a small garden adjoining the north wall of the mosque.