The motte (earthen mound) of Windsor was constructed by William the Conqueror in about 1080, and the castle has been added to and remodelled almost continually ever since. Edward IV began St. George's Chapel, which was finished by Henry VIII, who was buried there along with his third wife Jane Seymour. The Old Chapel, at the east end of St. George's, was remodelled by Henry VII. The Old Chapel eventually became the Albert Memorial Chapel after the death of Queen Victoria's husband.

Henry VIII also built a new gate for the lower ward, now known as the Henry VIII gate, and is the exit for tourist visitors to the Castle. Mary I built the Military Knights' Houses in the lower ward. Henry VII also built a new range to the west of the State Apartments. Elizabeth I added the Long Gallery to Henry VII's new apartments, and this area now houses the Royal Library.

The North Terrace was originally constructed by Henry VIII, although it was later widened.