@saab,
Ye Olde Cheshire Cheese, London
The cellar bars, vaults, are series of tiny stone rooms. These vaults were part of the original guest house’s chapel. The steps continue into the cellar proper which dates to a 13th century Carmelite Monastery which once occupied this site and are now another bar and dining area.
... and exactly there was the first European A2K gathering, in March 2003.