Bannerman Castle was built long after many other castles fell into ruin, but that doesn't make it any less interesting. It was inspired by the castles of Scotland and created by Francis Bannerman, who had made his fortune in munitions and bought Pollepel Island in the Hudson Highlands with some of his profits.
The building, with its turrets and forts, was part warehouse and part residence, and also provided a handy space for Bannerman to advertise his business. Soon after his death in 1918, a munitions explosion partially destroyed the complex, while a fire in 1969 left it in ruins. It's now looked after by a trust who holds walking tours there during the Summer.