Roman Agora, Athens

One of the most interesting sights of Plaka is the Tower of the Winds. This unusual marble tower (which served as a water clock) was built by an astronomer in the first century BC. On each of its eight sides is a depiction of a directional wind. The tower is part of the Roman marketplace—a large building with a spacious courtyard that was constructed in the first century BC. It is flanked by two gates east and west of the market. A 15th-century mosque can also be seen on the site.