THEY CALLED IT Project X. It was an unusually audacious, highly sensitive assignment: to build a massive skyscraper, capable of withstanding an atomic blast, in the middle of New York City. It would have no windows, 29 floors with three basement levels, and enough food to last 1,500 people two weeks in the event of a catastrophe. But the building’s primary purpose would not be to protect humans from toxic radiation amid nuclear war. Rather, the fortified skyscraper would safeguard powerful computers, cables, and switchboards. It would house one of the most important telecommunications hubs...