Camp of Diocletian
Palmyra, Syria
The Camp of Diocletian was a Roman military complex, or castra, built in the ancient city of Palmyra in the Syrian Desert. The complex was built under the Roman Emperor Diocletian in the late third-century CE and served as the military headquarters for the Legio I Illyricorum.
Archaeological site data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).