Located on Pollepel Island on the Hudson River, Bannerman Castle once acted as arms storage for Frank Bannerman, a Scottish munitions dealer in New York City. Bannerman and his wife eventually built a glamorous, castle-like home on the property, and resided there during the summer.

After a powder explosion in 1920, several fires, and various changes in ownership, the castle is not the breathtaking sight it once was, but Bannerman's name can still be seen plastered on what remains of its facade. Today, visitors interested in the historic site can tour the island via passenger boat or kayak.