Church of Agios Dimitrios, Thessaloniki built
601 CE.
Shown on the map at 40.639°, 22.948°.
The Church of Saint Demetrius, or Hagios Demetrios (Greek: Άγιος Δημήτριος), 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.
Text from the Wikipedia article Hagios Demetrios, licensed CC BY-SA 4.0.