A lavish, Gilded Age estate once owned by one of the richest men in the world just hit the market for under $6.5 million. Take a look inside.

Nestled along the banks of the Hudson River in the village of Irvington, New York, lies Villa Nuit. Its current owner says it's one of the last remaining Gilded Age estates — a home built in the late 1800s by the world's super-wealthy.

Marty Dolan, 64, told Insider he grew up in Irvington in the 1980s, watching great houses once owned by the likes of the Rockefellers, the Vanderbilts, and the Carnegies "chopped up" into smaller properties.

As a child, Dolan – who just put his 4.78-acre estate on the market for $6.49 million – said he remembers playing in the yards of these empty estates before seeing them disappear.

"I was a little kid in that village, and you couldn't miss it," he said. "If you were in someone's estate playing around with your friends, and then three weeks or three years later they were developing the townhouses, you would see that, and you'd feel that."

"There were about 40 or 50 estates that were set up by the wealthy in the 1800s," he said, most of which have now been demolished and divvied up into condos.

According to Dolan, his estate had a lucky escape in the 1970s.

The owners at the time "had enough," he said. But before it could be bought by someone else, the newly established National Trust caught wind of the sale and intervened, he said.

"There was a deal done where the new owners of the villa were given a tax deduction by donating the development right to the National Trust," Dolan said. "And that's how Villa Nuit was temporarily saved from being divided up."

Dolan, an investment banker, spent 12 years in London with his then-wife and three children but decided to move back to the US in 2000 before his eldest entered high school.

His parents still lived in Irvington, so he and his family always spent summers vacationing in the town that he said is about the size of a "shoe box."

As Dolan was selling a townhouse he'd renovated in South Kensington, London, he saw a $4.5 million listing for Villa Nuit in a small advertisement. It's a moment he describes now as "sheer luck."

"When we bought the house, it was already restricted," Dolan said.

Given its status in the National Trust, nobody could make changes to the exterior, which he said is built from limestone carved in France and shipped to the US by the original owner in the mid-1800s.

"It seemed to bother some people; it didn't bother me at all," he added. "I said, 'Okay, well, who would wanna change the exterior of the house anyway?'"

According to Dolan, the man who first built the mansion was a cotton exporter from a town called Nuits-Saint-Georges in the Dijon region of France.

"He built what was in 1852 in the US one of the first architecturally driven houses," Dolan said. "He got a European architect, and he said, 'I wanna build a house with the showpiece, not just the home.'"

One of the well-known prior owners of Villa Nuit was British business magnate John Jacob Astor IV, one of the richest men in the world when he died, Insider reports.

He and his second wife, Madeline Force, were first-class passengers on the ill-fated Titanic cruise liner, which sunk in 1912. While Force survived, Astor was one of the 1,500 people who died in the tragedy, according to the UK National Archive website.

His body was recovered at sea and later buried in Trinity Cemetery, New York.

From 1980 until he bought it in 2000, Dolan said a couple kept Villa Nuit as a second home.

"They found a perfect place to hang out on the weekends where nobody bothers them, and they renovated the house as far as they could," he said.

He said that the couple emptied the house of all the things that were defunct or wrong with it.

"My family and I bought it as a shell to complete the renovation," Dolan said.

One of the more crucial renovations Dolan said he did to modernize the estate from when it was originally built in the 1850s involved landscaping.

The driveway, he said, was still designed with small "twisty turns" to accommodate a horse-and-carriage, making it less than ideal for a car.

"Everything, in the end, had gotten bigger," he said. Delivery trucks arriving at the house would end up destroying the lawn and causing a commotion, he said.

"So we spent a lot of money and energy on making the landscaping and the driveways work for the modern world," Dolan said.

Renovations lasted years, but changes came and went periodically, Dolan said. The first issue was making sure the home was livable for his family, and then they added things like a Gunite heated swimming pool.

Both Villa Nuit and his former home in London required renovations, which Dolan said he enjoyed doing.

Though his primary job was being an investment banker, he said he picked up construction skills from his time working as a member of an Irvington community college grounds crew in his childhood.

With both projects, Dolan said he had "a bit of money, not a lot," which meant he got his own hands dirty with renovations.

From the roaring fire in the billiards room to the intricate handmade molding on the ceiling of every room, Dolan said Villa Nuit makes him feel like he's stepping back in time.

Dolan said when he would walk around the house, he could almost picture the workers in the 1800s building it.

According to the listing, Villa Nuit features plenty of new additions that make it suitable for modern living. These include a media room and gym.

Dolan said he and his family made several discoveries in their historical home through the years.

One such occasion occurred when they noticed pieces of wood in the basement were covering up flooring that didn't look quite right – on closer inspection, he said they found a hole that once played an essential role in maintaining a Gilded Age home.

After studying the house plans, the family realized it was an old coal shoot.

The 12,564 square foot villa comes equipped with nine bedrooms and eight and a half bathrooms on top of having a guest house on the estate, according to the listing.

After Dolan's now-adult kids moved out of the family home, he said he felt ready to begin a new chapter outside Villa Nuit.

"It's a lot of real estate for one person," Dolan said.

Dolan said his favorite room in the entire villa has to be the greenhouse conservatory, built by a company called Lord & Burnham in the 1800s.

While he said that its primary use back in the day was to grow vegetables, it became his favorite spot to cozy up and observe the changing of seasons.

"It's wonderful," Dolan said. "In the winter, it's incredibly bright and beautiful. In the spring and autumn, you get wonderful breezes in and out. It's an incredibly beautiful space."

"This rare Gilded Age estate, with gated entry, sits on five landscaped acres with pool and guest cottage offering an unparalleled lifestyle just 25 miles from NYC," Joy told Insider via email.

"I'd just grown up in this little village, and I was very sad to see all the old estates get divided up or burned down," he said. "Here was my chance to save one."

Having rescued Villa Nuit from developers, Dolan said he hopes to hand it over to someone who appreciates it.

"You really feel responsible that it should be here," he said. "When people come to the villa, they're like, 'I can't believe it's still here.'"

Dolan feels lucky to have been a chapter in Villa Nuit's history.