Harbaqa Dam

A Roman-era Palmyrene gravity dam, probably from the 1st or 2nd century CE, [Harbaqa](https://en.wikipedia.org/wiki/Harbaqa_Dam) was built with a concrete core faced in ashlar and later reused by the Umayyads in the 8th century. It once impounded about 5 million cubic meters of water and fed a canal serving nearby Qasr al-Hayr al-Gharbi. Its preservation is unusually good, largely because the isolated desert setting spared it from later quarrying.

Homs, Syria