The Ceremony of the Keys takes place nightly in the Tower of London. The 700 year old ceremony sees the Yeomen Warders locking up each of the Tower gates in turn with the Queen’s Keys. At Traitors’ Gate there is a traditional challenge of “Who goes there?” When all is locked the guard is inspected on Tower Green. The whole procedure takes exactly 7 minutes, ending as the clock chimes 10pm with the sounding of the Last Post. It is now largely, though not entirely, ceremonial, as the Crown Jewels are kept in the Tower.
Visitors can watch the Ceremony free of charge, but must apply in writing well in advance. See the website for details.