How did a Roman temple and a cathedral become the Great Mosque of Damascus?

The Great Mosque of Damascus grew out of the walls of a Roman temple and a Christian cathedral, because the city's Muslims needed more room and the caliph al-Walid I decided to build a monument. The site had been a place of worship since the Iron Age, when the Arameans built a temple to their god of rain, Hadad. Greeks linked the god to Zeus, the Romans turned it into one of the largest temples in Syria, and in 391 Emperor Theodosius I converted it into a cathedral.

After the Muslim conquest of Damascus in 634, part of the cathedral became a small prayer house, a musalla. It could not hold the growing number of worshippers, and the city lacked free space for a large mosque. In 706 al-Walid took the cathedral's site, returned other properties in the city to the Christians as compensation, and built the Umayyad Mosque. He is quoted telling the people of Damascus that they already had a fine climate, water, fruits and baths, and that he wanted to add a fifth thing: this mosque.

The builders kept the old walls and reused the church's columns and arcades. But they also invented something. Earlier mosques, like the Prophet's Mosque in Medina, were plain halls of columns. Damascus added three parallel aisles and a central nave leading from the entrance to the mihrab, probably influenced by Byzantine basilicas. This gave the building a monumental focus and influenced early Islamic architecture.

The walls glittered with what was, by some estimates, the largest area of gold mosaics in the world, mostly landscapes and buildings and, notably, no human or animal figures. Today it is considered the oldest mosque still in use in its original form, though fires and wars have forced many repairs.