Penthouse That Inspired Christian Grey's Apartment in 'Fifty Shades of Grey' Goes Up for Sale

It was listed earlier this week and is now under contract.

— -- A penthouse apartment that inspired the home of character Christian Grey in the novel “Fifty Shades of Grey” actually exists.

The 5,170-square-foot dwelling, listed at $8.8 million on Zillow, boasts floor-to-ceiling windows, 24-hour concierge service, a lap pool, theater room and private elevator.

The windows provide 280-degree views over the city of Seattle, Washington.

"[Author] E L James searched the internet for inspiration and came across this listing. ...She used the concept for Christian Grey's residence," said Scott Wasner, founding director at Realogics Sotheby's International Realty. "My clients bought it in 2010. E L James came to Seattle for a book signing and visited my clients and toured the unit in person, and confirmed that it was her inspiration."

Although the apartment is still listed for sale, Wasner confirmed to ABC News that the home went under contract on Sept. 14 -- just 24 hours after it was posted.

Additional features include an exterior living space, a private spa and a gym with a yoga studio.

The best-selling book was made into a movie starring Jamie Dornan as Christian Grey and Dakota Johnson as his love interest, Anastasia Steele.