Tower of London is a UNESCO World Heritage Site. The foundation stone was laid in the reign of William the Conqueror. In his reign The White Tower was built. In the 12th century, King Richard the Lionheart enclosed the Tower with a curtain wall and had a moat dug around it and filled with water from the Thames. Henry VIII (1509-47) continued the work begun on the royal residential buildings by his predecessors, but on a grander scale.