The mystery of the strange anti-gravity hills

In various regions of the world are mysterious places that seem to manage to defeat gravity - in their cars, off speed, coasting uphill and cyclists to strain to be able to descend the hill.
Known as gravitational hills, these strange natural phenomena can be found in places like Kanfyuzhan Hill in California and Magnetic Hill in Canada. Naturally, all surrounded with a healthy dose of rumors about magical effects and giant magnets buried in the ground.
But what happens to all these places?
It turns out that the strange phenomenon is just an optical illusion. It is so good and convincing that it is impossible to believe in it without precise physical equipment.
But if you just measure the height difference between the top of gravity hill and the bottom will see that everything is upside down and "tip" is lower than the "valley".

source: Science Alert