The House of Mystery in Gold Hill, Oregon was originally built by the Old Grey Eagle Mining Company in 1904 as an assay office. This company stopped mining gold in 1911. A few years later this assay office slid off of its foundation on an angle and has been that way ever since.
The history of the surrounding area, The Oregon Vortex, goes way back to the time of the Native Americans. Their horses would not come into the affected area. The Native Americans called the area the "Forbidden Ground", a place to be shunned. Many years before The House of Mystery was built it was noted that unusual conditions existed there. A place where balls that roll uphill and your own height is in question. It was not until well into the 20th century that any effort was made toward a scientific analysis of the disturbance.
John Litster was a geologist, mining engineer, and physicist. He developed the area in the early 1920's and opened it to the public in 1930. He conducted thousands of experiments within the Vortex. After Litster’s death on December 4, 1959, his wife Mildred sold the Oregon Vortex to Irene and Ernie Cooper, whose daughter Maria and grandson Mark have continued to keep the attraction open to the public.
I believe these photos came from a brochure pack that included a map complied in the 30's or 40's. I found a few of these photos and was inspired to find more information. This gal has some additional photos and scans.