Clarence House, London

Clarence House, which served as the Queen Mother's London residence for nearly five decades until her passing in 2002, is now the home of Charles, the Prince of Wales, and his spouse, Camilla, the Duchess of Cornwall. This Regency mansion, constructed in 1828 by architect John Nash for the Duke of Clarence (who later became King William IV), was built because the Duke found the nearby Saint James's Palace too cramped for his tastes. However, post-World War II renovations have resulted in little of Nash's original design remaining.

If you wish to visit Clarence House, you must book a guided tour in advance (as they are in high demand), and be prepared for security checks and restrictions similar to those at airports. Besides getting a glimpse behind the scenes of a functioning royal residence, the primary attraction is the display of 20th-century British paintings by artists such as Augustus John and Walter Sickert.