Chioggia, the working person's Venice, at the southern end of the Venice lagoon.
However, my health leads me away from places with staircases, so we turn to another option - Ravenna. Also at this eastern end of the Pianura Padana, the valley of the Po river. Where Chioggia is on the sea, Ravenna was on the sea but a thousand years of silt have placed the town inland.
These two places are very different from each other, but they share in common that they are slightly off the main tourist track.
Capital of the Western Roman Empire a millenium and a half ago, Ravenna retains astonishing mosaics in remarkable condition. A small town easy to walk. And with places either at ground level or with elevators.
Photos are from Wikimedia Commons.