The Tower of London owes its name to its oldest building, the White Tower, which stands in the centre. This keep has been much modified since it was first built in the 11C. It acquired its name during the reign of Henry III when its walls were whitewashed. The fortress residence of the English sovereign, it was for centuries an arsenal and today displays numerous items from the Royal Armouries. Note also the fine Norman chapel of St John the Evangelist.