ATM came in at number 2 on this creepy list. They might be confusing 'creepy' with 'other-worldly' or 'amazingly unique' though.
"The cave of Actun Tunichil Muknal is also known as 'The Cave of the Stone Sepulcher.' The cave plays host to numerous skeletons, but what makes it even creepier is the fact that most of the skeletons belong to sacrificed children. Many of the remains and artifacts are completely calcified to the cave floor. One of the cave’s most notorious features is the skeleton of a teenage girl, whose bones have been calcified into a crystallized appearance. This skeleton is known as 'The Crystal Maiden.'"