Jill Jonnes, author and New York historian, tackles her biggest project yet: the New York train system. Her newest book, Conquering Gotham, details the efforts of the Pennsylvania Railroad to bring a train system to New York some 100 years ago. The company had to overcome insane financial, logistical and engineering challenges; spar with Tammany Hall, the de facto political power of the city; and perhaps the greatest problem of all: how to tunnel beneath the Hudson and East Rivers?

Listen as Jonnes sits down with Diane Rehm and discusses the finer points of railroad building.