If you’ve taken the Metro-North Hudson Line upstate, odds are you’ve glanced out the train window and seen a curious sight: a small, rocky island in the middle of the Hudson River, topped with what appears to be the ruins of a European castle. 

But this isn't the Danube, this is Pollepel Island, a 6.5-acre island in the shadow of Storm King Mountain that was once home to the largest military surplus arsenal of its age. Unlike many crumbling ruins, which are often closed to the public, you can actually visit this one—and learn plenty of Hudson Valley history while you’re at it. 

Today, the island is a thriving destination for history and nature buffs alike. Best of all, the experience is easily reachable via Metro-North, and there's even an MTA Bannerman Castle Cruise and Walking Tour package. It’s a beautiful ride on the Hudson Line from Manhattan to Beacon. Once you arrive, the Beacon Institute Dock where you’ll meet the boat to Bannerman is a short walk from the station. 

In addition to the MTA package, The Bannerman Castle Trust offers regular tours of the island between May and November. You can take a combination cruise and walking tour, a kayak tour, or pair a self-guided tour with a live concert (all $40 per ticket). Any of these will give you ample opportunity to explore both the island’s natural and manmade features. The best reason to visit Bannerman, however, is to learn about the unusual history of the island. 

A Brief History of Pollepel Island 

Pollepel Island was formed 10,000 years ago during the last ice age, and it has spent most of those millennia uninhabited. Before European settlers arrived in North America, the banks of the Hudson were inhabited by members of the Lenni-Lenape, Algonquin, and Wappinger tribes. As far as archaeologists know, Native Americans never lived on the island, which at the time was a barren rock with no sources of food, but likely used as a lookout. Legend has it the island was believed to be haunted.

Though it was owned by wealthy local families on and off, no one lived on Pollepel. As such, it became a prime spot for ne’er-do-wells to live it up away from the mainland. Fed up with the drunken carousing, a local teetotaler named Mary Taft bought the island in 1888. 

Pollepel remained Taft’s until Francis Bannerman, the son of Scottish immigrants, bought it in 1900. Bannerman started what would eventually become a booming military surplus business when he was only 12 years old. His warehouses were situated in Brooklyn and Manhattan until the city government intervened for the sake of public safety, and he had to find a new place to store his munitions. 

Bannerman was a castle enthusiast, and he built the island’s four arsenals in their image. The grandest—and the one most prominently viewable today—was Arsenal 3, modeled after a castle he’d seen on a trip to Belgium.

One summer day in 1920, Francis’ widow, Helen, was relaxing on a hammock in front of the main house and went in for a glass of iced tea. Meanwhile, a spontaneous spark ignited the powder in one of the arsenals, causing a massive explosion that boomed across the area, shattering windows as far north as Poughkeepsie. Mrs. Bannerman herself narrowly escaped death—when she came back outside, a chunk of the building was nestled in the hammock she’d just been lying in. 

Though Francis’s progeny continued operations into the 1960s, the island fell into disuse and was sold to the State of New York in 1967. Then a second disaster occurred: In 1969, a fire of mysterious origins burned for three days and nights, gutting the remaining arsenals on Pollepel. The island fell out of use and memory until 1993, when the Bannerman Castle Trust took over its stewardship. It opened to the public in 2004.

How to Experience Bannerman Castle

There are a few different ways to experience the wonder of Pollepel Island and Bannerman Castle yourself other than the Bannerman's Island Cruise and Walking Tour package. All of the experiences offered by the Trust below cost $40 per person.

From Beacon Station, cross the tracks to the river, and you’ll find a dock where you can meet the Estuary Steward, a boat that will take you on a 30-minute ride down the river to the island. From there, you’ll enjoy a guided 90-minute walking tour of the island to learn about its history and legacy before being ferried back to the mainland. If you have a kayak or canoe, you can take your own trip to the island and go on a self-guided tour at a reserved time slot. A castle historian will take you on a 20-minute tour. 

If you don’t have a kayak of your own, Hudson-area tour group Storm King Adventure Tours will take you on a 2.5-hour guided tour of the river ($70), kayaking past Storm King Mountain and Breakneck Ridge before arriving at Pollepel Island. Though you can’t disembark at the island, your guide will give you a brief history of the area. 

The Trust also hosts music nights with local artists, which include a ride on the Estuary Steward, a self-guided tour of the island, and a performance.

Editor's Note: This was originally published on 8/27/21. It has been updated with the 2022 MTA Away Deal.

Jenna Scherer is a writer, journalist, and editor whose work has appeared in Rolling Stone, Time Out New York, The Village Voice, Condé Nast Traveler, and CNN Travel. Read more of her writing at jennascherer.com.