Museum of the First Congress of the Russian Social Democratic Workers' Party

Brace yourself for 'Guernica'

This museum has a fantastic collection, primarily 19th and 20th century art - surrealism, cubism, pop art, abstract expressionism - and Spanish artists are really well represented. It's spacious and filled with light, and a pleasure to wander around. There's also a lovely garden out the back where you can sit and process all the masterpieces you've just seen (or just spin out at the strange doll-sized park benches scattered around the grass - creepy!). Although it's an old building, the external glass-fronted elevators are a super-modern touch, allowing visitors to gaze out at the sprawling plaza below and the splendid Atocha station nearby.

But it's Picasso's 'Guernica' which most people come here for - and with good reason. Seeing this huge painting in the flesh is an overwhelming, emotional experience. Picasso's fury vibrates off the canvas, and you notice details that simply get lost in printed reproductions. It's breath-taking and powerful and moving.