In the early 1960s, two avant-garde contenders for the future of world urbanism represented equally brilliant and problematic alternatives. Plug-in City, by Archigram's Peter Cook, and New Babylon, by the former Situationist Constant, were megastructures drawn and designed in markedly different ways, promising dissimilar spatial experiences and different socio-economic strategies—Plug-in City's was pragmatic and market-based, New Babylon's was of an existential, non-market idealism. Though both proposals would be swept away by the post-modern turn, the dialectic they presented is still present in architecture a half century on. An advance caution to readers: this is a rare instance of an academic piece beginning with a profanity.