Mysterious road or Sinbiui Doro in Korean, also called a Ghost Road is one of the place that I can recommend you to visit in order to find out what is really happening once you get here. It's really a mysterious place. As you see, the road is going down a few meters away to sinbiye doro.
Here's the location where you can experience how mysterious the road is but first you have to go to straight a little bit more and make a u-turn. When you make a u-turn the road is going up. It's the opposite road of the bottom picture.
You will see this "Start Here" sign.
From the start sign, don't step on your car's acceleration and you'll experience the car moving. It is called a mysterious road because cars roll uphill with the engine turned off. As you go up, the car goes faster, too. You can also see people putting bottle on the road and the bottle roll up, too. Isn't it a mystery?
They say it's an optical illusion but still it's a best place to visit and have a great experience in driving to Korea.