• The Suffolk County Vanderbilt Museum is a must-see for any “Gilded Age” fan.
• The museum was once the estate of William K. Vanderbilt II, the son of William and Alva Vanderbilt.
• Alva is the inspiration behind Bertha Russell, who is played by Carrie Coon on the show.

Can you hear “The Last Great American Dynasty” playing in the distance?

There are many historical mansions on Long Island, but only one was once owned by the legendary Vanderbilt family. The 42-acre estate of William Kissam Vanderbilt II, which included his summer “cottage” of Eagle’s Nest, is now a museum that’s open to the public.

Eagle’s Nest was first built in 1910 as a small cottage, but as William II spent more time there, it expanded until 1936, when a full redesign was finished; it had become a 24-room Spanish Revival mansion.

William II spent time at Eagle’s Nest until his death in 1944. His will stipulated that, upon the death of his wife Rosamund, the estate would be left to Suffolk County and would become a museum, which it did after her death in 1947.

The Vanderbilts are one of the best-known (and richest) families in American history — so much so that Bertha Russell, the main character on HBO’s “The Gilded Age,” is based on Alva Vanderbilt, William II’s mother. In fact, a major plot line in season three is based on William II’s sister, Consuelo Vanderbilt, marrying the Duke of Marlborough in 1895.

So, as a new fan of “The Gilded Age,” I knew I had to check out Eagle’s Nest — even if Larry Russell isn’t really based on William II, I still needed to see the real mansion that his character might live in.

The museum is open every day except Monday and Thursday, and tours of the mansion are offered on Sunday, Tuesday, Friday, and Saturday. Tickets for the museum range from $8 to $14, depending on age, while a guided tour of the mansion is an additional $8.

Here’s what it was like to set foot in the home of a Vanderbilt.

On the North Shore of Long Island, about 40 miles outside New York City, lies the Suffolk County Vanderbilt Museum.

Inside the grounds are hiking trails, gardens, and a gift shop.

There’s also the Charles and Helen Reichert Planetarium, which holds multiple shows daily.

The biggest attraction, though, is Eagle’s Nest, the 24-room mansion of William K. Vanderbilt II, the great-grandson of Cornelius Vanderbilt.

Before I toured the home, I visited the museum grounds.

At the entrance stood a pair of stone eagles, which were taken from Grand Central Terminal. Cornelius Vanderbilt himself commissioned the train station.

One of the first things I did was head toward the Rose Garden; sadly, most of the roses had already bloomed.

But the landscaping was still immaculate.

Even if the roses were already gone, the views of the Long Island Sound were worth it.

Then it was time to head over to Eagle’s Nest.

Eagle’s Nest was originally built in 1910 as a small cottage. It expanded over the next three decades to become this Spanish Revival-style mansion.

The courtyard was set up for Shakespeare readings, which happen throughout the summer.

One side of the mansion is a natural history museum.

The other side is preserved to be just as the Vanderbilts left it in the early 1900s.

This was unlike any other historical mansion I’ve seen on Long Island, which are usually modeled on medieval castles or Tudor mansions.

Source: Business Insider

These cobblestones were taken from the streets of Greenwich Village in Manhattan before the streets were paved over.

Upon entering the home, the first thing you see is the staircase. It was imported from a Belgian castle.

There are portraits of William II’s family in the entryway. This is his father, William Kissam Vanderbilt. He ran an arena you may have heard of: Madison Square Garden.

Pictured top right is William II’s mother, Alva Vanderbilt. She inspired Carrie Coon’s character, Bertha Russell, on “The Gilded Age.”

The first room I saw was the dining room.

The ceiling is constructed from Florida cedar, or Southern Red cedar.

In the corner is a beautifully crafted fireplace. The floor tiles were imported from Portugal.

Next to the formal dining room is the butler’s kitchen. At the height of William II’s entertaining, 36 servants worked at Eagle’s Nest.

With a view as great as Eagle’s Nest’s, of course there’s a screened-in veranda.

Off the veranda is the Portuguese sitting room, named for the ornate fireplace imported from Portugal. It was constructed in 1494.

Here’s one of the guest rooms open for display. Each guest room had its own closet and bathroom.

Then, it was time to go upstairs and view the rest of the mansion.

One upstairs sitting room was almost entirely covered in dark wood. It also housed a giant organ.

A portrait of William II’s sister Consuelo can be seen in this room, in the bottom left. She coined the term “heir and a spare,” which she used to refer to her sons with her first husband.

Source: Town & Country

She was married to Charles Spencer-Churchill, the Duke of Marlborough. If their marriage didn’t produce children, his title would’ve gone to his first cousin, Winston Churchill.

Here’s one of the guest bathrooms at Eagle’s Nest. Note the marbled walls and tub.

This was William II’s bedroom. The room is bright, with beautiful views of the water — he probably had a great view of his 264-foot yacht, the Alva.

In addition to loving the sea, William II was an avid race-car driver, naturalist, and golfer.

His bed, seen here, was a to-scale replica of the bed of Napoleon Bonaparte.

These buttons, right by his bed, were connected to the servant’s staircase. He could summon his butler, and lock or unlock the servants’ stairwell.

In his bathroom, nods to his love of the water included a large ship on the floor. He also had a shower, which was somewhat unusual for the time.

To get to his wife’s quarters, I had to pass through the breakfast room.

Like the rest of the home, it had a lovely view of the water.

William II had two wives — this is how the bedroom looked when it was occupied by his second wife, Rosamond Lancaster Warburton.

This is her changing room and bathroom.

Rosamund’s tub is made of rose marble — a nod from William II to his nickname for his wife.

As I left the living quarters, I reached one of the entrances to the museum. This room is dedicated to William II’s son, William K. Vanderbilt III.

Inside were specimens collected by William II’s son on a 1931 trip to Africa.

The scenes reminded me of the American Museum of Natural History in New York City, which made sense — the same designer and taxidermist, William Belanske, did both.

This is a portrait of William III during a safari in 1931. He died two years later in a car crash at 26.

While it was time to exit this wing, there was still the rest of the museum to see.

The other half of the mansion is filled with specimens the elder William collected on his trips around the world.

There’s also a miniature replica of his yacht, Alva. During World War II, he donated it to the US Navy, and it was renamed the USS Plymouth. It was sunk by U-boats in 1943.

There are multiple rooms that are filled with sea creatures. William II himself discovered multiple species during his travels.

Down a final set of stairs was a basement filled with more relics from William II’s life.

There were also two of his cars parked and awaiting a driver (and probably a tune-up).

As I exited the home and crossed the courtyard, I was surprised to learn that there was even more to see.

I followed a sign for even more “habitats.”

I don’t know what I was expecting, but it wasn’t a giant whale shark hanging from the ceiling.

Another room was dedicated to large predators. It had a taxidermied lion and a tiger, but my favorite was the polar bear.

The exit brought me to the back of the house. I decided to go back to the central courtyard to see if I had missed anything.

And I had! There was a small doorway that led to Eagle’s Nest’s backyard.

The house was set on a hill, so the yard was multi-level.

First, I walked to the right.

There was a large reflecting pool.

Then I walked to the left and came across another fountain and some well-manicured hedges.

But the main attraction was, once again, the view.

The lawn was open, so I decided to trek down and see what structure at the bottom was.

To my surprise, it was a filled-in saltwater pool.

They’d even left the ladder in.

There were also changing rooms.

With that, I had seen almost everything the Vanderbilt Museum had to offer, with the exception of a few hiking trails.

I left the museum with a greater understanding of the Vanderbilts — and ready to keep watching “The Gilded Age.”