Mystery Sport is a tourist attraction near Santa Cruz, California. This place is famous because of its disrespect to the laws of physics and gravity.
The odd cabin, although seems like lying on flat ground, makes those who enter inside swinging all the time. The most probable theory that tries to explain this says that it’s all about “tilt-induced visual illusion. The illusion experienced by visitors results from the oddly tilted environment as well as standing on a tilted floor. Inside the tilted room of the Mystery Spot misperceptions of the height and orientation of objects occur. Even when people are standing outside on a level ground, the slant of the building in the background causes misperceptions as we judge the height of people using the slant of the roof rather than the true horizon.”