The Geological Museum
This venerable old institution was absorbed by the neighbouring Natural History Museum in 1985 but still has something of a separate identity. Unsurprisingly, devoted to all things geological with especially popular exhibits on vulcanology and earthquakes and fossils of all types

This venerable old institution was absorbed by the neighbouring Natural History Museum in 1985 but still has something of a separate identity. Unsurprisingly, devoted to all things geological with especially popular exhibits on vulcanology and earthquakes and fossils of all types
Check the official site before travelling; hours and prices can change.
More museums

Sir John Soane's Museum
Free, tiny, deranged — Soane's own house preserved exactly as he left it in 1837.

The Wallace Collection
Free national museum in a Manchester Square townhouse — armour, Boucher, the Laughing Cavalier.

The British Museum
Free, vast, civilisationally heavy — go for one room, not all of them.
Source: wikivoyage