There were several reasons for the longevity of these buildings. The most important is that they are targets of little military value. The aim of the Blitz was primarily to target British industry and infrastructure. The first targets to be hit in London were the aircraft factories scattered around the south and west of the conurbation. These were followed by raids on the industrial areas in the north and east of the city, as well as strikes on the Docklands along the eastern part of the Thames. For example, the first big daylight raid on the 7th of September 1940 dropped bombs mainly on the city's docks, damaging Commercial and Millwall Docks, as well as the subsidiary ports of Tilbury and Thameshaven outside the city. Night raids were also aimed primarily at the docks and warehouses, but the difficulty of navigating at dark meant bombs fell all over the city. The massive night raid on London on the 29th December 1940 was aimed at the warehouses of the City of London and Tower Hamlets. Whitehall and Westminster were thus saved partly by their distance from the main centres of industry.

A second reason is that British firefighters made serious efforts to save buildings of cultural significance. When St Pauls was threatened by the firestorm of the 29th December, (an event immortalised in the image St Paul's Survives by Herbert Mason) the building's firewatch made a heroic effort to extinguish any incendiaries near the building. Similarly, when the Palace of Westminster was bombed on the 10th-11th May 1941, firefighters managed to save Westminster Hall, albeit at the expense of the Commons Chamber.

One must also not neglect the inaccuracy of bombing raids from this period. Bomber formations were capable of targeting little more than a city - and even then weren't great at it. In 1941, the Butt Report found that only a third of RAF bombers were making it to within 5 km of their target. The Germans did have slightly better navigation, using radio aids such as X-Gerat, but they were still inaccurate. Bombing raids targeted at the docks on the Isle of Dogs scattered bombs from Biggin Hill to Tottenham, with a few bombs dropping as far from the centre as Borehamwood.

A final point I wish to make is that many significant buildings didn't survive the bombing (or didn't survive it in their original form). As mentioned above, the Commons Chamber was burned out on the 10th-11th May 1941 - it would take nine years for it to be rebuilt to its present form. Most of the churches of the City of London were destroyed by fire, including seven originally designed by Christopher Wren. A further nine Wren churches were destroyed or heavily damaged by the bombing, but were rebuilt over time. Many halls of the London Livery Companies were destroyed, along with the Inner Temple Library, and Holland House.

From a local perspective very few of Liverpool's best known buildings survived without some damage but plenty only saw minor damage, a lot was pure luck since enough bombs fell near to the Pierhead for example to suggest there was no plan to avoid hitting certain high profile targets (assuming that the bombing could be that accurate once over the target).

To name a few major buildings, The Custom House was all but destroyed and had to be demolished, the Liver Buildings and Cunard buildings suffered minor damage, the Port of Liverpool building was badly damaged by a parachute mine, the Town Hall badly damaged and the White Star Line Building badly burnt out. The set of civic buildings (main library, museum etc) on William Brown street were severely damaged but St George's Hall survived largely unharmed. India buildings was burnt out, but Martins bank opposite got away without serious damage. The head post office was burnt out and Government Buildings destroyed, but the Municipal Annexe (which the latter backed onto) was hardly touched.

Quite a lot of major buildings appear up have survived without damage because the damage inflicted on them was by fire rather than high explosive, so if the external structure survived, the interior would be rebuilt and it would be hard to tell, especially since the most buildings we see today have had their old interiors replaced long ago by he march of progress