The district has become increasingly commercial , with many offices in converted houses and new buildings , though the trend has been reverted in places . The United States embassy announced in 2008 it would move from its long established location at Grosvenor Square to Nine Elms , Wandsworth owing to security concerns , despite constructing an £ 8m security upgrading after the September 11 attacks including high blast walls . Since the 1990s , residential properties have become available again , though the rents are among the highest in London . Mayfair remains one of the most expensive places to live in London and the world and there remains some exclusive shopping and London 's largest concentration of luxury hotels and many restaurants , particularly around Park Lane and Grosvenor Square
September 11 attacks
September 11 attacks
Mayfair