The City's population fell rapidly in the 19th century and through most of the 20th century, as people moved outwards in all directions to London's vast suburbs, and many residential buildings were demolished to make way for office blocks. Like many areas of London and other British cities, the City fell victim to large scale and highly destructive aerial bombing during World War II, especially in the Blitz. Whilst St Paul's Cathedral survived the onslaught, large swathes of the area did not and the particularly heavy raids of late December 1940 led to a firestorm called the Second Great Fire of London.