The owner of a home in Queens has not given much thought about the origin of the concrete and steel room buried beneath his basement. “When I bought this house, nobody came to see this,” said Francisco Lago, who purchased his two-story home about 30 years ago. “It was in ruins.”...

Yet this unimpressive cramped space hidden away on a quiet block is a surprising link to a momentous period in American history: It is the only stand-alone private space remaining in the city to qualify as a bomb shelter, according to city records, a vestige of the cold war era when underground sanctuaries were promoted as offering refuge from a mushroom cloud....

Besides being a historical curiosity, this forgotten room carries a tangible benefit — a tax break that has saved the Lagos thousands of dollars over the years. They are one of the few remaining beneficiaries of a bill passed by the state’s Legislature in 1961 that provides exemptions for shelters designed “in accordance with plans, regulations and orders of the State Civil Defense Commission.”...