Diporto
It's the savvy locals' treasured secret—and one of Athens's oldest tavernas—where everyone wandering around Omonia Square has been welcomed through the years. Owner-chef Barba Mitsos keeps everyone happy with his handful of simple, delicious, and dirt-cheap homemade dishes, from the always exceptional horiatiki (Greek salad) and buttery gigantes (giant beans in tomato sauce) to saucy boiled meats with vegetables and tiny fried fish. Wine is drawn directly from the barrels lining the walls. As for decor, the feeling is authentic 1950s Athens. There is no sign on the door: just walk down the staircase of this corner Neoclassical building.