1969 plans to build an underground nuke-proof Manhattan.
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.