This is where Anne Boleyn was beheaded and Queen Elizabeth I was held prisoner. It’s also where the Crown Jewels are held and “Beefeaters” stand guard. If you plan a few months in advance, you can send away for tickets to the “Ceremony of the Keys,” a fascinating, 700-year-old tradition in which the guards ceremonially lock up the Tower for the night. Whatever your plans, make sure you allow at least a full day for this attraction—there is much to see and a lot of history to take in.