Pavlopetri

The archaeological site known as Pavlopetri (Greek: Παυλοπέτρι) is found in Vatika Bay, off the coast of southern Laconia in Peloponnese, Greece. It is about 5,000 years old, making it the oldest submerged city known in the world. Pavlopetri is unique in having an almost complete town plan, including streets, buildings, and tombs.

Archaeological site data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).