In Prosser, Washington, there’s a road that inclines upward. But if you put your car in neutral at the bottom, your car will start rolling “up” the hill. This isn’t the only place like this in the world, either. There are a number of hills where gravity seems to work in reverse.
But the real cause of this seeming violation of one of the fundamental laws of the universe is an optical illusion. The hills actually slope slightly downward, allowing your car to roll in what appears to be an upward direction. The optical illusion relies upon an obscured horizon, which means you have no good point of reference. There’s also a phenomenon where what appears to be a flat surface is actually at a slight upward incline, which bicyclists call a “false flat.”