Oct 13, London

It's surprisingly hard to decide on the tallest building in the world. Architects are much like Hollywood stars in their tendency to try to add a couple of sneaky inches. The people at the Council on Tall Buildings and Urban Habitat, who adjudicate on these matters, have had to ban all kinds of Cuban-heel equivalents, from enormous radio masts to metal "guy-ropes" holding up towers that would otherwise collapse in strong winds...more