'Oscar 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.'
“Manhattan could have a half-dozen such atomic cities strung under the city proper…the real problem in an underground city would be the lack of views and fresh air, but its easy access to the surface and the fact that, even as things are, our air should be filtered and what most of us see from our window’s is somebody else’s wall.”
Alison Sky and Michelle Stone. Unbuilt America. McGraw Hill, 1976, page 192.