Back in the late 1960s, and early 1970s, AT&T built a series of nuke resistant bunkers. The typical specs were concrete walls 36" thick, self contained turbine generators, water and air purification, plus rations to last up to 6 months. Some of those facilities are still around and operating (including one not far from me). I would expect that the switching gear of todays vintage takes up much less space and power th…
I don't think you were referring to these, but there are actually a few windowless, fortified concrete skyscrapers in New York that were built as telephone switching centers. Here's one in Lower Manhattan that is 29 stories: http://en.wikipedia.org/wiki/33_Thomas_Street They were likewise designed to withstand nuclear fallout. Because telephone switching equipment has shrunken over the years they now rent out some of…
Actually no. The ones I'm referring to were (usually) built way out in rural areas, where they were away from the expected blast area of a hit on a major city. The one I'm aware of is built mostly underground, then backfilled so that it looks like a natural hill (a hill with a concrete top, and a big microwave tower).
Some of these facilities were rumored to have ground entry points for a system called Combat Ciders ... http://www.fas.org/nuke/guide/usa/c3i/combat_ciders.htm