The house was built in 1910 as a summer home for Wallace Hurtte Rowe (1861–1919), the founder and president of the Pittsburgh Steel Company.

Cottesmore Hall was one of several mansions built in Cobourg by wealthy American families, who in the late 19th and early 20th centuries made the town a summer colony.

Rowe hired Pittsburgh architects Rutan & Russell, who designed a Colonial Revival house clad in white stucco.

Cobourg emerged as a wealthy summer colony through the growth of its transportation infrastructure and because of resource development in Northumberland County.

[1] Prior to the American Civil War, iron deposits had been discovered in Northumberland Country at Marmora and Blairton.

He acquired the property from Vincent Howard, a Methodist minister whose wife was a descendant of Benedict Arnold.

Rowe's estate was bounded on the east by a creek that flows into Lake Ontario, and on the west by Cottesmore Avenue.

[5] The iron gates on King Street were made by the Canada Foundry Company and cost several thousand dollars.

He gave generously to St Andrew's Presbyterian Church, founded the local golf club, and provided the hospital its first X-ray equipment.

However, the following year, Dunbar's successor, William Ernest Hamilton, decided the property was unsuitable for this function due to its proximity to a major highway.