At this roadside attraction, cars and bottles roll uphill and water flows the wrong way. It seems like some sort of strange trick of science, or perhaps even magic. Locals claim it’s because there’s a four percent decrease in gravity here.

Dubbed the Karpacz Gravitational Anomaly, this part of the road is well mapped on tourist maps and guides. Visitors drive there, then watch as their cars seem to roll uphill.

But as entertaining as the low gravity theory may be, this place is actually what’s called a gravity hill. The road moves downhill with a very slight slope for about a kilometer after which it slopes up slightly. This creates an optical illusion called the gravity hill effect, which is caused by a partially or completely obscured horizon tricking our brain into seeing an uphill slope where there is none.