Tate Modern

This converted power station houses one of the world's largest modern art collections, with Picasso, Matisse, and Rothko sharing space with video installations and conceptual pieces. The massive Turbine Hall - five stories tall and football-field long - showcases rotating large-scale installations that use the industrial space brilliantly. The permanent galleries organize art thematically rather than chronologically, so you'll find Warhol pop art next to contemporary digital work.

The building itself is half the experience. You enter through the sloped ramp into the cathedral-like Turbine Hall, then take escalators up through galleries that still feel industrial despite the white walls. The viewing level on floor 10 genuinely delivers - St Paul's sits perfectly framed across the Thames, with the City's skyscrapers stretching east. The space never feels cramped even when busy, thanks to the building's massive scale.

Skip the audio guide and just wander - the thematic organization means you'll stumble across unexpected connections between artists. The restaurant is overpriced and average; grab coffee from the level 2 café instead. Most people rush to the view, but the Turbine Hall installation deserves 20 minutes minimum. Evening visits after 6 PM are noticeably quieter, and the Thames views are better with London's lights coming on.