We’re not horsing around.

A 951-acre landmark Kentucky equestrian estate that once was home to 1896 Kentucky Derby winner Ben Brush and legendary sire Domino is on the market for a cool $57.5 million, Bluegrass Sotheby’s International Realty announced in a press release.

Located in rural horse country in Lexington, near the Kentucky Horse Park, 2469 Iron Works Pike belongs to the family of the late Irish billionaire Tony Ryan, who co-founded Irish ultra-low-cost airline Ryanair in 1984.

The property is anchored by a Greek Revival mansion dating to 1840 that spans 13,500 square feet and has seven bedrooms and 5.5 bathrooms, according to the listing.

If it doesn’t sell on the open market, the estate will be auctioned off as the final lot of the invitation-only Keeneland Championship Sale on Oct. 28, just before the Breeders’ Cup World Championships.

Called Castleton, the property has been associated with notable Thoroughbred champions, like Eclipse Award winner Gio Ponti, Grade 1 victors Jack Christopher and Gormley, and Longines Test Stakes winner Chi Town Lady. After retiring from his legendary racing career in 1966, Standardbred Bret Hanover became one of the most successful harness racing stallions in history while at Castleton.

With a bloodline that dates back to 1793, the estate includes an 1840 Greek Revival mansion flanked by ornate ironwork gates, as well as 16 barns housing 268 stables, staff quarters, a guest house, a covered bridge and an equine cemetery. 

Regarded as one of the most photographed farms in the Bluegrass region of Central Kentucky, Castleton was featured in the 2005 Disney film “Dreamer,” starring Kurt Russell and Dakota Fanning. 

“Castleton has existed as an equine operation for more than two centuries, whether with Standardbreds, Saddlebreds or Thoroughbreds, and we have been the sixth stewards of this historic farm,” said Ryan’s son, Shane Ryan, in prepared remarks.

Tony acquired the site in 2001 for $14 million and made subsequent upgrades before his death in 2007. Shane, who has run it as a horse-breeding operation while living on an adjacent site, is now ready to pass the reins.

He is now selling the historic farm because he spends most of his time in Europe and his children aren’t as passionate about equestrian life, listing agent Ken Donworth of Bluegrass Sotheby’s told the Wall Street Journal.