The layered city

Montréal boasts the largest underground complex in the world, which extends the life of the city deep into the domain of the Canadian winter. When the mercury drops to -35 C, it's still possible to ice-skate indoors, walk along miles of shop-lined thoroughfares, and eat at dozens of restaurants--all without braving the wind-chill.

But the underground city also thickens the physical complexity of the city in an unconventional way. Everyone who knows cities understands the importance of multi-story buildings in providing for additional density. The underground city, however, is more like a street than a skyscraper--it's more for moving about and socializing than for sleeping or working.

The great urbanist Jane Jacobs, in her 1961 magnum opus, The Death and Life of Great American Cities, suggests a distinction between the space in a city occupied by buildings (which I call "blocked space") and the space through which inhabitants may pass freely (which I call "thru-space"). Skyscrapers densify blocked space, but the underground city effectively thickens and enriches Montréal's actively used thru-space. Streets, in Jacobs's analysis, are more important to the life of a city than buildings (I really do encourage reading the whole book--it's one of the best I've ever read), and so making a city's thru-space richer and more complex greatly enhances the quality of life in a city.

Stockholm, without resorting to Montréal's tunnels or Minneapolis' skyways, creatively thickens its thru-space using at least three strategies I've seen:

(1) Bi-level plazas,

We let the buses think they can fly. They may be smug, but at least they're quiet.

(2) Multi-level transport,

Damn! How fast is the subway in Stockholm?

(3) Mysterious bridges. (I believe that the bridges, which often seem to emerge from and lead to nowhere, actually gentle the sometimes precipitous slopes of Stockholm's hills.)

Both bridges lead somewhere. Scout's honor.