Every now and again we encounter a retrofuturistic urban planning proposal that is equal parts whimsical and hilarious, such as the proposed million-person city spanning from New York to San Francisco. Here's something that eclipses that design in terms of comic impracticality. Behold Oscar Newman's 1969 plan to hollow out an entire, nuclear-resistant city under Manhattan. How on Earth would all of this space be made? Why, by burying nuclear weapons deep underground and detonating them, of course.
The notion of building back-up cities in case of emergencies still thrives (see: the modern plans for a clone Tokyo), but Newman's vision of a Morlock Manhattan was a bit of a rib-tickler. Explains John Ptak of this scheme over at Ptak Science Books:
The author of this plan speculated on building this spherical city in Manhattan bedrock—a structure which so far as I can determine would have a volume of 1.2 cubic miles (5 km3) with its top beginning some 1,200' under Times Square [...] Newman published this in 1969 (?!) after somehow latching onto the idea of clearing out massive underground caverns with nuclear explosions—in this case, the space would be hollowed out under Manhattan. The underground sphere would be a miniature version of whatever was above it—along the medial there would be a "topside" of a regular city with streets and high rise buildings, underneath which would exist an underground city for the underground city. In this honeycomb would exist the means of production and energy, segmented in multi-block-sized enclosures of no charm.
My favorite embellishments are the giant "air filters" that overshadow skyscrapers topside and the wan Coca-Cola advertisement floating in the nether-deeps.