I toured Kykuit, a 40-room mansion in New York that once belonged to the richest man in the world. Take a look inside.

• Kykuit, a 40-room mansion in Sleepy Hollow, New York, belonged to the Rockefeller family.
• It was built in 1913 for John D. Rockefeller, founder of the Standard Oil Company.

At the height of his success, John D. Rockefeller's Standard Oil fortune comprised 1.5% of the gross domestic product of the United States. He was the world's first billionaire with a net worth of $1.4 billion in 1937 (around $29.5 billion today) and the richest individual in the world at the time.

Kykuit (pronounced "kai-kit"), a 40-room Classical Revival-style villa in Sleepy Hollow, New York, was his idyllic seasonal escape from city life.

Built in 1913, Kykuit belonged to four generations of the Rockefeller family before former New York governor and US Vice President Nelson A. Rockefeller left it to the National Trust for Historic Preservation after his death in 1977. The estate opened to the public in 1991.

Today, visitors can tour the home and its lush gardens overlooking the Hudson River through Historic Hudson Valley. Tours are available from May through November and range from $25 to $65 depending on length. I took the Classic Tour, which lasts two hours and 15 minutes and costs $45.

Take a look inside.

Kykuit is located in Sleepy Hollow, New York, about 30 miles north of New York City. I traveled there to look around the sprawling, historic estate.

The author (right) at Kykuit Mansion.      Talia Lakritz/Insider

Tours of Kykuit leave from the Visitor Center, where I perused a gift shop with books about the Rockefellers and crafts by local artisans.

The gift shop at Kykuit.      Talia Lakritz/Insider

I checked in at the front desk and received a wristband.

My wristband.      Talia Lakritz/Insider

A shuttle bus transports tour groups from the Visitors Center to the mansion — it's a quick five-minute drive.

The bus takes visitors to the mansion.      Talia Lakritz/Insider

As I disembarked the bus, I felt transported back in time by Kykuit's Classical architecture, which featured Roman gods, and its serene garden landscapes.

Kykuit Mansion.      Talia Lakritz/Insider

The lush wisteria growing up the sides of the mansion was imported from China in 1820, according to our tour guide.

Wisteria growing at Kykuit.      Talia Lakritz/Insider

Our tour guide also shared that Tiffany's created the glass torch lamps in the front yard.

The front yard of Kykuit Mansion.      Talia Lakritz/Insider

Sculptures from Nelson A. Rockefeller's vast modern art collection decorated the front porch.

The front porch of Kykuit.      Talia Lakritz/Insider

The raised step at the entrance was designed for the Rockefellers to easily disembark from horse-drawn carriages.

The entrance to Kykuit Mansion.      Talia Lakritz/Insider

Our first stop inside the house was the Office, which featured a copy of a 1767 portrait of Benjamin Franklin that hangs in the Green Room of the White House.

The Office in Kykuit.      Historic Hudson Valley

I could picture the Rockefellers hosting fancy gatherings in the Music Room, the largest room in the home. It used to contain an organ, but the original grand piano remains.

The Music Room in Kykuit.      Historic Hudson Valley

However, John D. Rockefeller and his wife, Laura, were devout Baptists, so they didn't serve alcohol while entertaining guests in the Dining Room.

The Dining Room in Kykuit.      Historic Hudson Valley

In the China Room, a set of dishes from Nelson Rockefeller's time as President Gerald Ford's vice president was embossed with "E Pluribus Unum" — "Out of Many, One" — which appears on the US' Great Seal.

The China Room in Kykuit.      Historic Hudson Valley

A portrait of Abby Rockefeller, the wife of John D. Rockefeller Jr., hung in the Alcove with standing lamps designed by 20th-century Swiss sculptors the Giacometti brothers.

The Alcove in Kykuit.      Historic Hudson Valley

Kykuit's Library functioned as a family room, where the Rockefellers would gather after Sunday lunches, according to our tour guide.

The Library in Kykuit.      Historic Hudson Valley

I was surprised to find a full art gallery in the basement furnished with works by Pablo Picasso and Andy Warhol, collected by Nelson Rockefeller.

An art gallery in the basement of Kykuit.      Historic Hudson Valley

"Kykuit" comes from the Dutch word for "lookout." At 500 feet above sea level, the mansion's terrace provided gorgeous views of the gardens and the Hudson River.

Gardens at Kykuit.      Talia Lakritz/Insider

Architect William Welles Bosworth designed different sections of the gardens to feel like different rooms, our guide said.

Gardens at Kykuit.      Talia Lakritz/Insider

In one area, rows of linden trees were precisely manicured to create an allée, from the French word for "alley."

An allée of trees at Kykuit.      Talia Lakritz/Insider

At every location on the grounds, I could hear the rippling sound of water fountains.

The Tea House on the grounds of Kykuit.      Talia Lakritz/Insider

The last stop on the tour was the Rockefeller family's stables and garages, where they kept their stagecoaches and vintage cars.

Vintage cars at Kykuit Mansion.      Brian Haeffele/Historic Hudson Valley

With Kykuit's Classical architecture, impressive art collection, and manicured gardens, I felt like I was visiting a historic villa in Europe.

Kykuit Mansion as seen from the gardens.      Talia Lakritz/Insider