In the redwoods outside Santa Cruz, a small cabin sits on a hillside where people seem to lean and balls seem to roll uphill. The attraction's website calls it a gravitational anomaly. Wikipedia describes it as a gravity hill, a visual illusion caused by the tilted surroundings and the tilted floor.
History
George Prather, who was inspired by the Oregon Vortex, started the attraction, according to Wikipedia. The article gives two dates: 1939 for the opening, and June 1941 for when it opened to the public. Prather died in January 1946. His partner was Vaden McCray. Life magazine featured the Mystery Spot on Nov. 15, 1948.
Visiting
The official site lists hours of 10 a.m. to 4 p.m. on weekdays and 10 a.m. to 5 p.m. on weekends, with tours every half hour. Parking is $5 per vehicle. Visitors should arrive 30 minutes before their tour, and the attraction says weekend tours often sell out around noon, so buy tickets ahead. It is celebrating Halloween all month and invites visitors to come in costume.