Back in the 1960s, a group of UK design radicals got together and formed Archigram, an art collective whose creations (like this "walking city") have become synonymous with architectural futurism.
The idea behind the walking city is simple: Instead of humans walking around the city on foot, the city itself can walk. It's perfect for nomads who live in a constantly-shifting urban landscape.
Meanwhile, some of their other designs are weirdly prescient, such as this moon vehicle, which looks strangely similar to a moon vehicle in development now (see below). For more Archigram madness, check out their gallery.