On a cool evening in early November, I rented a car in Wichita, Kansas, and drove north from the city through slanting sunlight, across the suburbs and out beyond the last shopping center, where the horizon settles into farmland. After a couple of hours, just before the town of Concordia, I headed west, down a dirt track flanked by corn and soybean fields, winding through darkness until my lights settled on a large steel gate. A guard, dressed in camouflage, held a semiautomatic rifle. He ushered me through, and, in the darkness, I could see the outline of a vast concrete dome, with a metal blast door partly ajar. I was greeted by Larry Hall, the C.E.O. of the Survival Condo Project, a fifteen-story luxury apartment complex built in an underground Atlas missile silo. The facility housed a nuclear warhead from 1961 to 1965, when it was decommissioned. At a site conceived for the Soviet nuclear threat, Hall has erected a defense against the fears of a new era.