Secret subway

In 1869, Alfred Beach wanted to build America's first air-powered railway below New York City, but Boss Tweed, powerful politician and notorious crook, opposed. Working under night cover, Beach and his crew carved a three-hundred-foot tunnel beneath a department store. Before long, the project was discovered and the public raved about its potential. But no further tunnels were ever built. What happened to Beach's railway, and where is it now?.