The National Maritime Museum
Museum devoted to the maritime role in Britain's history. Contains the UK's national collection of Maritime artefacts (although do not expect much in the way of whole ships). One of the buildings housing the museum is the Queens House, built by Inigo Jones as the first Palladian

Museum devoted to the maritime role in Britain's history. Contains the UK's national collection of Maritime artefacts (although do not expect much in the way of whole ships). One of the buildings housing the museum is the Queens House, built by Inigo Jones as the first Palladian
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