At the intersection of Knyaz Boris I and Preslav streets in central Varna, a cafe occupies a building whose floor incorporates a glass section revealing Roman remains from the 3rd and 4th centuries AD. The ruins — sections of wall, tile, and structural foundation from the ancient city of Odessus — sit in a shallow excavation beneath the current floor level, with lighting installed to make them visible to anyone walking past or sitting at a nearby table.
It is a small display by the standards of, say, Rome or Naples, where Roman remains turn up under buildings routinely. But in context it's a good reminder that Varna is built on a continuously occupied site going back two and a half millennia, and that the distinction between ancient city and modern one is partly a matter of depth. Stop in for a coffee and have a look through the glass — the coffee will be fine and the ruins are genuinely 1,700 years old.