Armstrong believed that Montana's high altitude and the nutrient-rich farmland along the Jefferson River made the location ideal for raising superior racehorses.
 He owned horses that raced at major US tracks, including a horse, Lord Raglan, who finished third in the 1883 Kentucky Derby.
In 1885 or 1886, bought the mare Interpose, in foal, and shipped her to Montana.
Her foal, Armstrong's chestnut race horse, Spokane, was foaled in the barn in 1886, and the horse's early training was on the barn's indoor track.
After being shipped east at age 2 for race training, Spokane  won the Kentucky Derby in 1889, defeating the favorite, then went on to win other major eastern races.
Although popular legend states he returned to Montana, there is not evidence that he did so.
 He was advertised as standing at stud in Kentucky.

The Panic of 1893 caused financial hardship for the Doncaster operation.
 Armstrong sold the ranch to Max Lauterbach and left Montana in 1900.
From there, the barn was owned by a number of different people, and fell into disrepair until purchased by the Bayers family, who owned the Doncaster Farm property from 1933 until 1997.
Arthur and Elizabeth Bayers raised Hereford cattle and were major breeders who sold their stock all over North America and held a cattle sale every year in the barn.
 Their son, Byron Bayers, estimated that their cattle sales over the years topped $5 million.
The barn's upkeep was very expensive, particularly the cost of red paint.

The Bayers sold the parcel of land where the barn sat in 1985, and it again fall into disrepair.
In 1997, it was purchased by real estate developer and local rancher named  Allan Hamilton, who began to renovate the building.
 He had a new roof put on the building and re-leveled the foundation.
  In 2010, the property was purchased by Tony and Amie James.
 They formed Swift River investments, a Massachusetts-based business, and began to renovate the structure into a community center.
 Though "everyone" thought it had been listed on the National Register of Historic Places, no one had done so.
 In January 2015, the Montana Historic Preservation Board met and unanimously agreed to nominate it.
 The structure was placed on the NRHP on April 14, 2015.

The building was a Montana Cowboy Hall of Fame Legacy Award Inductee in 2008.
The Jameses had been willing to donate the building to house the Montana Cowboy Hall of Fame itself, but a location in Big Timber, Montana was ultimately selected.
Armstrong believed that Montana's high altitude and the nutrient-rich farmland along the Jefferson River made the location ideal for raising superior racehorses.  He owned horses that raced at major US tracks, including a horse, Lord Raglan, who finished third in the 1883 Kentucky Derby. In 1885 or 1886, bought the mare Interpose, in foal, and shipped her to Montana. Her foal, Armstrong's chestnut race horse, Spokane, was foaled in the barn in 1886, and the horse's early training was on the barn's indoor track. After being shipped east at age 2 for race training, Spokane  won the Kentucky Derby in 1889, defeating the favorite, then went on to win other major eastern races. Although popular legend states he returned to Montana, there is not evidence that he did so.  He was advertised as standing at stud in Kentucky.
The Panic of 1893 caused financial hardship for the Doncaster operation.  Armstrong sold the ranch to Max Lauterbach and left Montana in 1900. From there, the barn was owned by a number of different people, and fell into disrepair until purchased by the Bayers family, who owned the Doncaster Farm property from 1933 until 1997. Arthur and Elizabeth Bayers raised Hereford cattle and were major breeders who sold their stock all over North America and held a cattle sale every year in the barn.  Their son, Byron Bayers, estimated that their cattle sales over the years topped $5 million. The barn's upkeep was very expensive, particularly the cost of red paint.
The Bayers sold the parcel of land where the barn sat in 1985, and it again fall into disrepair. In 1997, it was purchased by real estate developer and local rancher named  Allan Hamilton, who began to renovate the building.  He had a new roof put on the building and re-leveled the foundation.   In 2010, the property was purchased by Tony and Amie James.  They formed Swift River investments, a Massachusetts-based business, and began to renovate the structure into a community center.  Though "everyone" thought it had been listed on the National Register of Historic Places, no one had done so.  In January 2015, the Montana Historic Preservation Board met and unanimously agreed to nominate it.  The structure was placed on the NRHP on April 14, 2015.
The building was a Montana Cowboy Hall of Fame Legacy Award Inductee in 2008. The Jameses had been willing to donate the building to house the Montana Cowboy Hall of Fame itself, but a location in Big Timber, Montana was ultimately selected.
Doncaster Round Barn