A gravity hill, also known as a magnetic hill (and sometimes a mystery hill or a gravity road), is a place where the layout of the surrounding land produces the optical illusion that a very slight downhill slope appears to be an uphill slope. Thus, a car left out of gear will appear to be rolling uphill. There are hundreds of gravity hill locations around the world.
These "paranormal" sites also tend to have names like "Haunted Hill", "Magnetic Hill", or "Anti-gravity Hill", reflecting attribution of the properties of the area to such "mysteries" as the supernatural or magnetism. While humans also have a sense of balance to determine the inclination of the ground, visual cues can override this sense, especially if the inclination is shallow.