Built around 1365, it’s one of only two remnants left from the 1834 fire that ravaged the Royal Palace of Westminster. This stone three-level tower, once a moatside storehouse for Edward III’s treasures, has walls so thick it was later considered an ideal setting for taking accurate measurements. So you’ll see some explanation of weights-and-measures standards and some relics dug up from the moat (a 1,200-year-old sword, a bulbous bottle from The Sun, a 17th-century tavern where Samuel Pepys drank). It’s quiet and easily overlooked.