Buckingham Palace has a long history, starting as a large townhouse built in 1703 and later acquired by King George III for his wife Queen Charlotte in 1761. It became known as the Queen's House and has served as the administrative headquarters and official London residence of the British monarch since the 19th century. When the Queen is in residence, the royal standard flag is flown above the palace. The palace offers tours on days when the Queen is not present and sells traditional souvenirs. Inside is housed the Royal Collection.