Spain

Gaudí began the Sagrada Família in 1882 and told anyone who asked that his client was in no hurry. He is still right: the basilica is unfinished, and you can watch it being built around you. The Nativity facade he saw completed is the fussy, organic one on the east side; the Passion facade opposite is stark and angular and was carved long after his death, which is why the two look like different buildings. Go in the morning if you want the eastern windows, late afternoon for the western ones — the stained glass throws colour across the nave and the hour decides which colour. Tower access is a separate ticket and books out first, so decide before you buy whether you want to go up.