Gravity hills, spook hills, and mystery spots are places around the world said to be gravitational anomalies. You set your car into neutral at the base of the hill, and wait for it to mysteriously creep up the slope. Such hills have long had roadside attraction appeal for those who like to dabble in the paranormal, and the cause of the phenomenon has been attributed to everything from ghosts to aliens to magnetic forces.
In actuality, these are not warped vortexes in the Earth’s gravitational field—they’re just optical illusions. Though cars, water, and marbles appear to roll up hill, they are really rolling downhill, just as they should be. The horizon line and other features of the landscape trick the brain into perceiving the slope as uphill. Still, it can be hard to convince the brain otherwise. Gravity hills continue to evoke shock and awe in all those who turn off the highway to experience them.