Banqueting House
Designed and built in 1619-1622 by the Neo-Classical architect Inigo Jones, The Banqueting House is now all that remains of Whitehall Palace, the sovereign's principal residence from 1530-1698 when most of it was destroyed by fire. Renowned for its architecture and paintings (by

Designed and built in 1619-1622 by the Neo-Classical architect Inigo Jones, The Banqueting House is now all that remains of Whitehall Palace, the sovereign's principal residence from 1530-1698 when most of it was destroyed by fire. Renowned for its architecture and paintings (by
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