I see that large numbers of New Yorkers want to rebuilt large towers at least as tall as the buildings destroyed on the WTC site. I sympathise - I think my preferred solution emotionally is a single, 220 storey tower in the shape of an upraised middle finger - but it won't happen. Firstly, although the people of New York might like to see such a skyline, it would be very difficult to find tenants for it, particularly on the higher floors. And, sadly, the Osama bin Ladens of the world would see it as a personal challenge to try and knock it down again, and it isn't worth that. (Osama bin Laden seems to have been driven to knock down the first one for in some ways curiously obsessive and personal reasons as well. In any event, the desire for enormous office buildings seems to have shifted away from the US and to Asia, from Malaysia to Hong Kong to Shanghai to Taipei, a couple of decades ago. New Civil Engineer ran a nice article on these Asian buildings a couple of months ago - another free but irritating registration required). It seems to me that the best approach to rebuilding on the WTC site is to see how to use the site to improve how well New York operates as a city. That largely means infrastructure improvement. There are various proposals to rebuild the 1 and 9 subway lines, as well as the PATH service from New Jersey in order to provide better interchange services and greater capacity in lower Manhatten. Plus there is an interesting proposal to extend the Long Island Railroad to a new terminus downtown - something that would not have been otherwise possible because there was nowhere to build turnaround facilities in Lower Manhattan. (There was an article on these proposals and others in the New Yorker last week - not on the web, sadly). I think these sort of opportunities to improve the infrastructure to something better than existed before is a more subtle, useful way of saying "up yours" to the terrorists. It means that in the long term, development of downtown Manhattan, in general, can grow to something more complex, and something greater than it otherwise could have, because we push the factors that limit development further into the distance.