When construction began in 1860, Sandy Point Farm was part of the original 280-acre waterfront Vanderbilt estate.

The property was designed by architect A.S. Walker. A decades-long project, the stables were completed in 1902. At its peak, it was considered one of the most prestigious horse farms in the United States.

"The property has been an iconic part of Portsmouth and American equestrian history for over a century," said Kelly McCraw, listing agent for Mott Chace International Real Estate.

The original owner, Reginald Claypoole Vanderbilt, was the son of Cornelius Vanderbilt, a horse breeder and avid sportsman.

During the Gilded Age, the Vanderbilts enjoyed a life of luxury at their summer home, the Breakers in Newport, RI. The young Vanderbilt spared no expense when it came to building the magnificent Portsmouth property.

Reginald is the father of fashion designer Gloria Vanderbilt and grandfather of CNN anchor Anderson Cooper.

Built using cypress beams, the structure features three separate rooflines and a cupola atop a 60-foot-high hill in the riding arena.

"These cypress beams are so beautiful that if you wanted to build this structure now, it wouldn't even exist today," McCullough said.

"I could see [the farm] turning into a therapeutic riding centre, like the Shea Centre in California," she added." It could also become a great equestrian centre, like a mini Hamptons, or it could become an extension of our counterpart in Wellington, Florida."

The six-acre site includes a 24-stall stable, a 15,000-square-foot indoor riding arena, "groom's quarters" and a guest lounge. It is being sold along with three adjacent parcels of land.

"Six acres sounds like a lot, but when the Vanderbilts owned it, the original property was over 180 acres," McCullough said." It's being sold as multiple lots, so there's a lot of potential."

McCollough hopes the new buyer will be someone who appreciates the property and its historical significance.

"The property," she says, "has been part of Equestrian America, so I could see it being given to a non-profit organisation to potentially save it." It is not protected from demolition. The property is not in a place with a historic district commission, which does not allow buildings to be torn down or have their appearance modified. We hope the next buyer will understand the importance of architecture and culture like Sandy Point."