To be highly visible - if you are an organization seen to be connected with a government, a regime, a religion, a belief system or simply wealth creation- may well now come to be considered unwise. The only way for an organization to safeguard itself against terrorist attack is fully to adopt the strategy of the terrorists’ own bases. This means becoming invisible. This in turn means rejecting large centralized landmark buildings, of whatever kind, in favour of a network of scattered, far smaller, anonymous buildings.

Corporate pride may be hurt by this, but logically there is no reason why centralization of people should be necessary anyway. Electronic communications, we have been told for years, should make large office buildings unnecessary. This seems in part to be coming true as more and more people work from computers at home. And yet the giant corporate and governmental HQs continue to be built.

The long-term effects of the September 11 terror attacks on America may affect the way every city in the world is built, and even threaten the whole notion of the dense urban centre: adherents of the loose net of small nodes will find themselves being listened to with increasing attention.

So much depends on the aftermath, the knock-on effects, of September 11, politically and militarily. We await the aftermath with dread, though it is just possible to make out a case for hope. Never to be forgotten are the images of trapped people standing in Yamasaki’s narrow windows high in the World Trade Center towers, choosing to jump to their deaths rather than be burned alive. As with similar images of the burning airship Hindenberg in 1937, this event marks a fundamental change in our perceptions and attitudes.