Anyhow, I just learned from this book that "The first leisure promenades in European cities were on top of abandoned city fortifications. These promenades came to be known as bollevarts, or boulevards, after the German bollwerk (bulwark)."
Now, we don't really have abandoned fortifications on which to build new public spaces here in America. But there is a growing trend of tearing down ugly downtown freeways to replace them with new parks and other walkable, humane public spaces. New York demoted its West Side Highway, and San Francisco removed the rubble permanently when the Loma Preita earthquake rendered the Embarcadero Freeway as useless and dangerous to cars as it had been for pedestrians. As a matter of fact, some people think that we ought to do something similar in my hometown of Portland, Maine.
60s-era freeways are kind of the opposite of medieval fortifications: instead of protecting the cities they encircle, they wage war against them with an assault of murderous vehicles, pollution, noise, and isolation. It's a credit to civilization in general that these aggressive structures are eventually abandoned and transformed.
But if European "boulevards" are an appropriation of Germany's bellicose "bollwerks", what should Americans call their reclaimed freeways? Cabrini Greens, perhaps? The parting of the Moses Seas? How about De-Detroits?