St James's Palace
The Mall,
London
SW1
Underground: 
Green Park
St James's Palace was built in the late-1530s by Henry VIII, on the site of St James's Hospital, one of London's few Tudor landmarks.
The palace was a main royal residence during the reign of Elizabeth I and 17th-18th centuries.Most of what is seen today is the result of remodelling by John Nash.
In 1952 Elizabeth II made her first speech here as Queen from St James's Palace, and it is still the Court's official headquarters.
Although closed to the public, you can explore Friary Court on Marlborough Road and attend Sunday services at the Chapel Royal.