The oldest and largest occupied castle in the world, #WindsorCastle dates back to the 11th century, when William the Conqueror began building it above the Thames. Forty monarchs have lived in the castle, many adding their grand touches—including George IV, who commissioned the famous Waterloo Chamber, an extended St. George Hall, and a new grand staircase, among other improvements. Following a devastating fire in 1992, Windsor Castle was carefully restored over the next five years at a cost of roughly $44 million. The #Castle is open to visitors Thursday through Monday, and tours include the state apartments, semi-state rooms, Queen Mary’s doll house, and St. George’s Chapel, where Queen Elizabeth II was laid to rest.