An anonymous Saudi billionaire just snatched up the former vacation home of Jackie O's family in one of London's wealthiest enclaves. Take a look inside.

• A residence at 47 Grosvenor Square once used by Jackie Kennedy Onassis' family sold within 24 hours of hitting the market. A Saudi billionaire bought it for $22 million.
• Grosvenor Square is an enclave in London's affluent Mayfair neighborhood.
• The apartment is considered a "trophy property" at 5,000 square feet with a 60-foot-plus balcony.

You know real estate is hot when it only sits on the market for 24 hours. It also helps if the property has a glamorous history — and high-profile former residents.

That was the case for the first-floor apartment at 47 Grosvenor Square in London's affluent Mayfair neighborhood. The property, which was once used as a London home by the Onassis family, including Jackie Kennedy Onassis, hit the market with an asking price of nearly $30 million. Within 24 hours, someone had scooped it up for $22 million.

Wetherell, the real-estate agency behind the deal, kept the buyer's identity anonymous but acknowledged the new owner is a Saudi billionaire. Peter Wetherell, founder and chairman of the agency, described the home in a press release as a "trophy property" — London properties that appeal to the global elite.

The apartment has yet to be restored since it was used by Onassis clan, and restoration could bump up its value even higher, to $35 million. At 5,000 square feet, the home spans nearly the whole width and depth of the building, and it's the only apartment in the building to have a 63-foot balcony overlooking Grosvenor Square.

Here's a look inside.

A residence at 47 Grosvenor Square was listed at $29.6 million and sold in less than 24 hours for $22 million to a Saudi billionaire.

Courtesy of Wetherell

The billionaire bought the home for his daughter, according to Wetherell, the real-estate agency behind the deal.

It's the highest price paid for a single, unmodernized apartment in Mayfair this year. The last time a piece of Mayfair property listed above $10 million sold in less than 24 hours was 10 years ago.

Source: Wetherell

Grosvenor Square has been a well-known enclave in London's affluent Mayfair neighborhood since the 18th century.

Courtesy of Wetherell

Over the years, aristocrats and politicians have flocked there. It was once home to Oscar Wilde and the US embassy. The building that housed the latter is now being transformed into a luxury hotel.

Source: Mansion Global

The residence used to be the London home of Artemis Onassis. It was used as a London pied-à-terre by members of the Onassis family, including Jackie Kennedy Onassis, in the 1960s and '70s.

Aristotle Onassis and Jackie Kennedy Onassis.      Courtesy of Wetherell

It's the first time in over 28 years that the Onassis family's Mayfair property hit the market and sold.

Before the Onassis family, it was first owned by Sir John Anderson, 1^st Viscount Waverley, who was chairman of the Royal Opera House.

Source: Wetherell

The building itself was erected in the late 1930s, designed in a palatial neo-Georgian style.

Courtesy of Wetherell

Source: Wetherell

The residence has yet to be restored since its glamorous early days. A restoration could bring its value up to $35 million, according to Wetherell.

Courtesy of Wetherell

Source: Wetherell

The first-floor apartment boasts 5,000 square feet of living space and is nearly as wide and deep as the building itself, with 10.3-foot ceilings.

Courtesy of Wetherell

Source: Wetherell

When you first walk in, there's a vast entrance hall.

Courtesy of Wetherell

Source: Wetherell

It leads to three adjacent reception rooms facing the square, comprising 60 feet in length combined.

Courtesy of Wetherell

Source: Wetherell

That includes the dining room and study, pictured here.

Courtesy of Wetherell

Source: Wetherell

There's also a library with built-in shelves to keep the books you'll take to the study.

Courtesy of Wetherell

Source: Wetherell

And there's a spacious family kitchen, as well as a bar.

Courtesy of Wetherell

Source: Wetherell

There are two large bedroom suites. One consists of three bedrooms off of the kitchen. The other includes one bedroom next to the library.

Courtesy of Wetherell

Source: Wetherell

Each has its own ensuite bathroom. There's also a guest bathroom and powder room in the apartment.

Courtesy of Wetherell

Source: Wetherell

There are a total of four ensuite bathrooms in the apartment. The other two are his-and-hers bathrooms as part of the master bedroom suite.

Courtesy of Wetherell

Source: Wetherell

They're each flanked by matching dressing rooms. The "his" dressing room features light wood and dark green marble accents ...

Courtesy of Wetherell

Source: Wetherell

... while the "hers" dressing room is more light and airy with a white palette.

Courtesy of Wetherell

Source: Wetherell

Outside, there's also a terrace overlooking the south side and a 63-foot-plus balcony. The apartment is the only one in the building that has a balcony overlooking Grosvenor Square.

The balcony.      Courtesy of Wetherell

Source: Wetherell