Dead Air Valley: "The Castle That Was a Warehouse"

Every commuter on the Metro-North Hudson Line knows the castle in the middle of the river. Almost none of them know it was never a castle. Francis Bannerman, the surplus king of 501 Broadway, needed somewhere to store Spanish-American War gunpowder he could not keep in Manhattan, so in 1900 he bought Pollepel Island and built a Scottish baronial warehouse, part arsenal, part family seat, part billboard. Silas Van Wyck tells the story of the 1920 powder house explosion, the 1969 fire, and the trust that keeps the walls standing today.