In other words, are tall buildings a prerequisite to competing in today's global economy? It's an interesting question. And Jason Barr -- professor of economics at Rutgers University-Newark -- does think they are an important ingredient. So much so that he wrote a book on the topic called, Cities in the Sky: The Quest to Build the World's Tallest Skyscrapers. While Jason does acknowledge that not every city needs them, he does suggest that not having them could hinder a global city:

If you look at Paris' global ranking in terms of its importance in the world economy, as measured by the size and number of international firms, it's falling. Paris in 2000 was ranked fourth, and by 2020, it was down to eight, losing out to skyscraper cities such as Singapore and Dubai.

In the last decade, Paris has shrunk by 122,000 residents. As reported by Forbes, "Many of those leaving are choosing either the suburbs or countryside around Paris, or they are relocating to France's smaller cities such as Bordeaux, Lyon, and Toulouse." By limiting its building stock, Paris is driving up housing prices, pushing out residents, and causing suburban sprawl.

While I agree that tall buildings are important "geography-shrinking machines", what we're really talking about is using land more intensely. We're talking about urban density. But you don't necessarily need tall buildings to have high population densities. Consider Barcelona, which is one of the densest cities in Europe, and consider this comparison between Paris (few tall buildings) and Vancouver (more tall buildings).

So is the argument simply that density is good for cities, and that tall buildings are one way to achieve that? Or is it that, now that cities like Paris are built out (albeit at very high densities), the only option for growth is to go up? I guess I'll have to read his book.