Nobody ever tells you to go to the Royal Courts of Justice, which seems silly. This neo-Gothic building is striking, and anybody can waltz in (and sometimes even watch a case as it develops, although I wouldn't necessarily recommend that, it's all rather dreary). They sometimes throw film premiere after parties or do fashion shows in here, and it provides the most dramatic backdrop you could ever imagine. Lavish party or no lavish party, this is really worth a look!
London WC2A, UK