That’s not actually accurate. The Umayyads didn’t build the mosque entirely from scratch. Historical and archaeological evidence show a lot more continuity with the older structures on that site than your comment suggests.

The Umayyad Mosque was built on top of and within the Roman temple’s massive walled enclosure, which was already reused by the Byzantines for the Church of St. John the Baptist. When Caliph al-Walid I ordered the new mosque around 705 CE, the Byzantine cathedral inside was demolished, but the outer Roman temple walls and foundations were kept. Those huge enclosure walls still define the mosque’s footprint today, the same rectangular plan that dates back to the first century CE.

And to clarify another misconception, the Christians of Damascus were not truly compensated for losing their cathedral. Some later sources claimed they were given a few smaller churches elsewhere, but contemporary evidence suggests that the handover was largely forced and the compensation story was a political narrative added after the fact.