Antique Real Photo Postcard, circa 1940s. A demonstration of a visual illusion experienced at "Mystery Spot" near Santa Cruz, California. (Sorry to say this, but you can hardly help but notice when standing on the right the posture of the men is tall and erect, but slumped over when they take their position on the left side.) Divided back, EKC stampbox, unused. Condition: Excellent condition. Comments: The Mystery Spot is a visual illusionbased tourist attraction near Santa Cruz, California, opened in 1941 by George Prather. Visitors of the Mystery Spot experience gravity-defying demonstrations on the short but steep uphill walk. The Mystery Spot is a popular tourist attraction, and gained recognition as a roadside "gravity box" or "tilted house" illusion. At this roadside attraction, the laws of gravity and physics seem to disappear as balls roll uphill and people lean over past their toes without tumbling over.