One of Philippines' many natural wonders in the Province of Bohol.
Vote for it to the "New 7 Wonders of Nature" here: www.new7wonders.com/nature/en/liveranking/
Legend has it that the hills came into existence when two giants threw stones and sand at each other in a fight that lasted for days. When they were finally exhausted, they made friends and left the island, but left behind the mess they made. For the more romantically inclined is the tale of Arogo, a young and very strong giant who fell in love with an ordinary mortal girl called Aloya. After she died, the giant Arogo cried bitterly. His tears then turned into hills, as a lasting proof of his grief.
However, up to this day, even geologists have not reached consensus on how they where formed. The most commonly accept theory is that they are the weathered formations of a kind of marine limestone on top of a impermeable layer of clay. If you climb the 214 steps to the top of the observation hill near the complex, you can read this explanation on a bronze plaque.
Source and more at: www.bohol.ph/article6.html