A little background for the curious:
Francis Bannerman VI built the castle just 50 miles north of New York City in 1901-1920 to store the military surplus supplies he was world-renowned for selling. In addition to the arsenal, Bannerman built a home for occasional escapes from the city and a small harbor to move his wares and bring guests.
As privately selling military surplus materials was made much more difficult, Bannerman’s business began to falter, and with it the castle. The island began a long decay in 1920 with the explosion of the munitions storage building, and it was all but abandoned in the 1950s.
Pollepel Island is now owned by the state of New York, and ferries in the summer months take the curious to hard-hat tours of the grounds.
The crumbling facade is all that remains of the castle, but it’s still a spectacular sight in a most unexpected location.”