So as the heat of the Cold War began to subside, John Hay made up his mind to convert his bunker into a luxury cavern that would be up for sale soon. He made a few tweaks to it, adding a “Fred Astaire dance floor” in the great room. “I didn’t know what to do, so I thought I would make it into a Hollywood home, and see if I couldn’t sell it for a decent price,” he was quoted explaining…