The challenge of building underground in Manhattan is clear. "We're building in the densest area that possibly exists. We have over 100,000 residents per square mile," Horodniceanu said to the Daily ... more 
The challenge of building underground in Manhattan is clear. "We're building in the densest area that possibly exists. We have over 100,000 residents per square mile," Horodniceanu said to the Daily Mail in a video. (Photo/ AP) less 
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Fri, Feb 8, 2013 11:00 AM EST