I visited an abandoned castle hidden on a New York island that's slowly crumbling away. It was hauntingly beautiful.

The abandoned Bannerman Castle is deteriorating on the Hudson River in New York. The island it sits on opened to visitors in 2020.
The abandoned Bannerman Castle is deteriorating on the Hudson River in New York. The island it sits on opened to visitors in 2020. National Archives and Records Administration, Joey Hadden/Business Insider
  • The abandoned Bannerman Castle sits on Pollepel Island in New York's Hudson River. 
  • Once a fortress for weapons, the castle is only accessible by private boat.
  • Today, the facility hosts tours and is used as a theater venue. Here's what it looks like.
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Sitting on Pollepel Island in New York's Hudson River, a stunning piece of history is slowly crumbling away.

Bannerman Castle was built as a fortress for weapons in the early 20th century by Francis Bannerman, a Scottish arms trader, The New York Times reported. The castle was abandoned in the 1950s after gunpowder exploded inside.

Then, in the early 1990s, the Bannerman Castle Trust led efforts to restore the structure and island to make it safe for the public to visit, according to the company's website. It's been accessible since 2004 and open for tours since 2020.

We got a private tour of the island in 2019 — before tours were available to the public. Take a look at Pollepel Island's decaying castle that's being taken over by nature. 

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Welcome to Bannerman Castle, an abandoned structure in New York's Hudson River that I visited in 2019.

Bannerman's Castle ruins
A view of Bannerman Castle from the Hudson River. Joey Hadden/Business Insider

Today, you can reserve tours on the Bannerman Castle website.

Bannerman Castle is on Pollepel Island, which is about 60 miles north of New York City.

NYC to Bannerman
Pollepel Island is in the Hudson River, north of Manhattan. Google Maps

The abandoned castle is visible from the Metro-North Railroad's Hudson train line.

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To get to the castle, I took a cab from the Manitou train station to Donahue Memorial Park in the town of Cornwall, New York.

Hudson River
The park sits on the west side of the Hudson River. Joey Hadden/Business Insider

There, I met up with guides from the Bannerman Castle Trust, the group that oversees the preservation and maintenance of the castle.

I boarded a boat on the park's dock with my guides.

Hudson River dock
A work boat at the Cornwall public dock. Joey Hadden/Business Insider

I crammed into the boat with two guides and a handful of volunteer gardeners who do landscaping work on Pollepel Island.

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Twenty minutes later, I arrived at the castle. From the dock, I thought its beautiful, sturdy-looking walls made the building appear almost functional.

Bannerman's Castle ruins
The north gate of Bannerman Castle on Pollepel Island. Joey Hadden/Business Insider

From the dock, we climbed 72 stairs to reach the island.

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But my guide told me I could not go inside — it's not safe.

A view of Bannerman Castle from the north trail of Pollepel Island.
A view of Bannerman Castle from the north trail of Pollepel Island. Joey Hadden/Business Insider

My guide explained that the towers of the castle are held up by external beams with braces made of steel. Each individual section weighs 250 pounds.

But even with this support, there's still a risk that the walls could fall.

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All visitors must stay at least 100 feet away from the castle.

Bannerman Castle limits
The north trail on Pollepel Island. Joey Hadden/Business Insider

Luckily, observation decks are set up around the castle at picturesque vantage points.

A history of accidental explosions and weather damage at Bannerman Castle has left the castle that was once a weapon fortress in this decrepit state.

Bannerman's Castle ruins
A warehouse wall (left) and a tower wall (right) held up by steel braces. Joey Hadden/Business Insider

Francis Bannerman VI, an arms dealer who lived in Brooklyn, bought Pollepel Island in 1900. He wanted a place outside the city to store an arsenal of munitions, according to The New York Times, so he built the fortress and an accompanying harbor.

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Bannerman's sons took over the business when he died in 1918. But in 1920, a room full of gunpowder exploded.

Bannerman's Castle ruins
A close-up of a Bannerman Castle wall shows where windows used to be. Joey Hadden/Business Insider

This shattered the castle's windows.

Forty-seven years later, the Bannerman family sold the island to New York State.

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A view of Bannerman Castle's tower from the observation deck. Joey Hadden/Business Insider

It eventually became part of the Hudson Highlands State Park Preserve, according to the park's website.

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In 1969, a fire destroyed much of the castle.

A view of Bannerman Castle and remnants of its harbor.
A view of Bannerman Castle and remnants of its harbor. Joey Hadden/Business Insider

After that, Pollepel Island was deemed unsafe and declared off-limits by the State of New York.

But in 1992, Neil Caplan, a resident of nearby Beacon, New York, formed the Bannerman Castle Trust.

Bannerman's Castle ruins
A view of Bannerman Castle walls from the Hudson River. Joey Hadden/Business Insider

The group raised money to restore the island; Caplan is its executive director.

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The Trust teamed up with New York's Office of Parks, Recreation, and Historic Preservation to open the island to the public in 2004.

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Bannerman Castle's tower as viewed from an observation deck. Joey Hadden/Business Insider

Today, it serves as a theater, museum, and historical site.

Although the main castle is inaccessible, the Trust stabilized another structure that served as the Bannerman family residence. That's now the island's visitor center.

Bannerman's Castle ruins
The Bannerman family residence is intact and safe to enter. Joey Hadden/Business Insider

The facade of the building also serves as the backdrop for the theater's stage.

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Inside, visitors can find information about the island's past.

Bannerman's Castle ruins
Historical information in the Bannerman Castle visitor center. Joey Hadden/Business Insider

Modest exhibits explain the site's history and the construction of the castle. Drawings and documents are framed on the building's distressed walls.

Visitors can also see preserved fixtures from the castle, like this bathtub.

Bannerman's Castle ruins
A bathtub that was saved from Bannerman Castle. Joey Hadden/Business Insider

The center also has a gift shop that sells art and T-shirts.

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Although the trust has restored parts of the castle since the 1990s, the weather has still taken a toll on the structure in recent decades.

Bannerman's Castle ruins
A view of Bannerman Castle from the Hudson River. Joey Hadden/Business Insider

According to the Bannerman Castle Trust, much of the castle's shell collapsed one night in December 2009. Then, just a month later, more walls fell during a winter storm.

On my way back from the castle, the boat took a spin around the island's perimeter.

Bannerman's Castle ruins
Remnants of Bannerman Castle's harbor. Joey Hadden/Business Insider

From the water, we caught glimpses of other pieces of the abandoned fortress, including its deteriorated harbor.

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From afar, it was especially clear that nature has already taken over many parts of this mysterious piece of history on the Hudson River.

Bannerman's Castle ruins
A view of the castle from the Hudson River. Joey Hadden/Business Insider

The combination of medieval architecture and overgrown trees and foliage makes Bannerman Castle a sight worth visiting up close.

Photos New York Castle
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