In 1904, Clise bought 78 acres of the property from homesteader John Tosh, and continued to buy surrounding property over the years. His first building on the site was a hunting lodge, which he later expanded into a mansion for his family.
Clise named his property Willowmoor and developed it into a working farm, raising award-winning Ayrshire cattle as well as Morgan horses. Willowmoor was so successful that in 1914, the Japanese government sent delegates to the farm to learn more about dairy production.
Clise sold his property in 1928, and the farm passed through various hands over the years. In 1956, the investment firm of Allison and Lean purchased the farm with plans to develop it commercially. At the same time, King County was seeking to buy land for parks, and Marymoor was the first on the list.
The Clise mansion later saw use as home to the Marymoor Museum of Eastside History, which opened its doors in 1967. In 2002, a $52 million shortfall in King County's budget led to the eviction of Marymoor Museum from the mansion to make room for more commercial ventures.