The Diamond Mountain Inn was originally known as the Janesville Hotel. The two-story wooden structure contained twenty-two rooms and was built by Dennis Tanner in 1872.
In 1913, B.R. Holmes acquired the hotel. It was in need of substantial upgrades. He named his new enterprise the Diamond Mountain Inn—the named remained until its demise.
Holmes operated the hotel for a brief period. It would change numerous ownerships over the years. In 1920, LeRoy Pollock was one of them, whose son Jackson Pollock would become well known in the modern art world.
On the night of December 6, 1931, J.C. Moore, the current owner, was awakened by the crackling sound of fire. He hastily escaped the burning building. A bucket brigade was quickly assembled, with all efforts to prevent the fire from spreading. The hotel was a total loss, and only partially covered by insurance. The origin was a defective flue in the dining room.