Convento do Carmo
The Great Lisbon Earthquake of 1755 left behind very little but rubble, but this resilient Carmelite convent, founded in 1389, somehow managed to escape total destruction. Today, the roofless structure packs a whole lot of wow upon first sight. The skeletal remains of its ruined nave and skyward-barreling Gothic arches are one of Lisbon's most astonishing—and ominous—highlights. The attached archaeological museum is also worth a stroll, as is plopping yourself down on leafy Largo do Carmo for a pitchers of refreshing sangria.