The Musée d'Orsay holds the world's richest gathering of Impressionist and Post-Impressionist painting — Monet, Degas, Cézanne, Van Gogh, Gauguin — inside a former railway station. You enter beneath an iron-and-glass ceiling that still feels like a platform hall, then climb to the upper floor where the paintings hang close and the light turns soft. Crowds cluster at Van Gogh's swirling self-portrait; quieter rooms hold Degas's dancers caught mid-stretch. On the top level an enormous transparent clock face frames Montmartre and the white domes of Sacré-Cœur.
The building was a railway station and it has never stopped looking like one. Its platforms were too short for modern trains within a few decades, and by the 1970s the hall stood under threat of demolition; instead France filled it with the art its own century had first refused. Walk the sculpture-lined aisle on the ground floor and you end at a golden clock still marking the hour, exactly as it did for departures.