By Erika Owen
November 18, 2016
Getty Images/AWL Images RM

Portugal is full of mystical places—the fairytale castles of Sintra, medieval castles, the palaces of Porto—but the existence of most of these spots can be explained.

The “Braga Bon Jesus” experience is, however, a little less common.

Braga, a small town about three-and-a-half hours north of Lisbon, is known as the “Portuguese Rome” for its stunning churches and architecture. The region dates back to the 3rd century, and many make the trek just for the Bom Jesus de Monte sanctuary, which translates to “Good Jesus of the Mount.” But it's behind this iconic structure that a true modern mystery awaits curious drivers.

It looks like an inconspicuous hill, but throw your car into neutral at the bottom of it and you're in for a surprise. Instead of continuing down the road, your car will climb backward up the hill. Check it out:

It seems like a mind trick, or a few drivers just looking to pull your leg, but there's an explanation behind why this happens—and there are plenty of other locations around the world where you can find the same situation. These special places are called gravity hills, or landscapes that appear uphill because of the surrounding landscape, but actually have a slight decline.

According to io9, most gravity hills are located in areas where you can't easily see the horizon in any direction, making it easy to obscure your perception of what's up and what's down.

Knowing this, it's easy to understand when cars “climb” a hill, or why water appears to flow upward. And physics aside, it's a great prank for an unsuspecting travel buddy.