NEW YORK – A generation of Americans knew just what to do in the event of a nuclear attack – or during a major false alarm, like the one over the weekend in Hawaii. Take cover in a building bearing a yellow fallout shelter symbol. But these days, that might not be the best option, or even an option at all. Relics from the Cold War, the aging shelters that once numbered in the thousands in schools, courthouses and churches haven't been maintained.