The Tower of London

The Tower of London, one of the city's great icons, has been an imposing fortress keeping both invaders and rowdy natives at bay since the early 1080s, when William the Conqueror ordered the construction of large fortifications on the Thames. The Jewel House, containing the Crown Jewels (though some may be 'in use'), and the White Tower, containing Henry VIIIs' armour, unmissable.