Driving down a remote stretch of County Road U in Wisconsin, you’ll come across two white letters painted in the middle of the road: GH. If you stop your car while pondering the meaning of these seemingly random two letters, your vehicle will begin to slowly move backwards up the hill behind you, and soon enough, the meaning of the “GH” will become quite apparent.

Gravity Hill in southwestern Wisconsin appears to defy gravity by seeming to pull cars left in neutral uphill. As your car “ascends” to the “top” of Gravity Hill, you will be traveling uphill at nearly 20 miles per hour, leaving you only to scratch your head in disbelief.

What trick of gravity is going on here? Something alien? A supernatural occurrence? Perhaps Newton was wrong all along? Actually, Gravity Hill is an optical illusion, a trick of the eye perfected by a slew of topographical elements in the area. Although the road at Gravity Hill is actually slanted downwards, visual cues in the surrounding region make it appear to be an incline.

The steep, tree-covered hill to the south of Gravity Hill blocks the horizon, removing key frames of reference and distorting the scene. The ridge at the “top” adds to the illusion, as the dip north of the ridge makes Gravity Hill appear to point upwards in comparison. Just when we think we know it all, Gravity Hill reminds us that perception is not always reality.