Hagios Demetrios
Thessaloniki Municipality, Greece · built 601
The Church of Saint Demetrius, or Hagios Demetrios, is the main sanctuary dedicated to Saint Demetrius, the patron saint of Thessaloniki (in Central Macedonia, Greece), dating from a time when it was the second largest city of the Byzantine Empire. Since 1988, it has been on the UNESCO World Heritage List as a part of the site Paleochristian and Byzantine monuments of Thessaloniki.
Church data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).