The central facade is the propylaeum from Roman times, which had been repurposed in the Christian church, and finally in the mosque.

The Great Mosque of Damascus constructed by the Umayyad caliph al-Walid I (reigned 705-715), is a seminal monument of Islamic architecture. The site chosen was the holiest in the city, having successively held temples to the Syrian storm-god Hadad and Jupiter Damascenus and the church of John the Baptist (the mosque still contains a shrine to John the Baptist). The prayer hall used the existing propylaeum and is laid out internally on an east-west axis like a Christian basilica.