London - Buckingham Palace
Buckingham Palace was built in 1703 as Buckingham House, for the Duke of Buckingham. King George III bought it in 1761. The palace was considerably enlarged over time. It became the Sovereign's official London residence with the accession of Queen Victoria in 1837. (That's a monument to Queen Victoria in front.) The east wing, which is shown in most photographs of the palace (including this one), was added in 1847. It includes the balcony in the center, where the Royal Family appears on important occasions.