London's location is the United Kingdom.
Greenwich Mean Time . The term `` GMT '' is especially used by bodies connected with the United Kingdom , such as the BBC World Service , the Royal Navy , the Met Office and others particularly in Arab countries , such as the Middle East Broadcasting Centre and OSN . London . London contains four World Heritage Sites : the Tower of London ; Kew Gardens ; the site comprising the Palace of Westminster , Westminster Abbey , and St Margaret 's Church ; and the historic settlement of Greenwich ( in which the Royal Observatory , Greenwich marks the Prime Meridian , 0 ° longitude , and GMT ) .