Design Museum
A must for anyone with an interest in modern and contemporary design. The permanent exhibition follows the change in British homes from the early 20th century until present day, which is constantly updated to include new design classics. There are temporary exhibits which run for

A must for anyone with an interest in modern and contemporary design. The permanent exhibition follows the change in British homes from the early 20th century until present day, which is constantly updated to include new design classics. There are temporary exhibits which run for
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