The Agora, Athens, Greece

Often overlooked by the hordes heading for the Acropolis is the ancient agora (market place). It's highlight being the 5th Century BC Temple of Hephaestos. There's also a small museum housed in a beautifully reconstructed stoa (colonnaded walkway) and a scattering of statues. It's an atmospheric site, with the bonus of dramatic views of the Acropolis looming above.