Alfred Waterhouse's terracotta cathedral of natural history is one of London's truly great free attractions, with eighty million specimens spanning four and a half billion years. The building itself, opened in 1881, is decorated inside and out with sculpted plants and animals — extinct species on the east side, living on the west — and the central Hintze Hall, with the blue whale skeleton hanging above the grand staircase, is one of the great theatrical entrances in any museum.
The dinosaur gallery is the perennial draw for children, with a long ramp past Triceratops, Stegosaurus and an animatronic T. rex. Older visitors gravitate to the Cocoon, an eight-storey research building you can walk through, and to the mineral and meteorite collections. The Earth Hall escalator — riding up through a giant rotating globe — is one of the best simple thrills in London for a five-year-old.
Skip the queues by entering through the Exhibition Road side, which is almost always quieter. Avoid weekends and school holidays if you possibly can; on a wet Sunday in February the place is a controlled riot.