Oregon Vortex

The Oregon Vortex is a roadside attraction that opened to tourists in 1930, located on Sardine Creek in Gold Hill, Oregon, in the United States. It consists of a number of interesting effects, which are gravity hill optical illusions, but which the attraction's proprietors propose are the result of paranormal properties of the area.
Background.
Prior to any construction of the area, local legend had it that Native Americans in the area referred to the site as a "forbidden" land, and travelers passing through would often find their horses refusing to go through the area.
A gold assay office was built in the area in 1904 by the Old Grey Eagle Mining Company, which slid from its foundation in the early tens, coming to rest at an odd angle. In 1914 the outpost and assay house were rediscovered by a prospector named William McCollugh. McCollugh convinced his friend, geologist and engineer John Litster to come to the US from his birth place in Alva, Scotland. Litster says he researched the paranormal phenomena of the so-called 165-foot magnet radius.
When Litster died in 1959, his wife sold the Oregon Vortex to Ernie and Irene Cooper. The Coopers' daughter Maria and grandson Mark kept the attraction open since then, making it one of Oregon's oldest examples of Roadside Americana.
Odd angles create an illusion of objects seemingly rolling uphill. The same effect can be seen in The Montana Vortex and house of mystery, Pennsylvania's Laurel Caverns, and at Santa Cruz, California's Mystery Spot. Two UC Berkeley researchers studied the Santa Cruz Mystery Spot and published their conclusions in Psychological Science in 1999. They proposed a framework called "orientation framing" which describes how the brain's visual processing uses spatial frames of reference. They noted similar illusions including the Ponzo illusion, the Zöllner illusion, the Poggendorf and Wündt-Hering illusions. James Randi, magician and illusionist, also described the Oregon Vortex (House of Mystery) as an optical illusion in 1998 using photography and mathematics to describe the illusion. Russ Donnelly, professor emeritus of physics at the University of Oregon visited the Oregon Vortex in 1966 and was convinced it was some sort of optical illusion. Owner Maria Cooper agreed with Donnelly that what people are seeing inside the House of Mystery is an optical illusion but insisted something else was happening outside the house that makes people's height appear to grow and shrink depending on their location. 
Oregon Vortex is also famous for "height change" as the apparent relative height of two people varies, depending on where each stands. The explanation of the strange phenomena is that they are caused by optical illusions. Distorted backgrounds that induce a forced perspective, as with an Ames room. The Oregon site also exhibits phenomena similar to those perceived by visitors at the mystery spot located outside St. Ignace in the upper peninsula of Michigan.