I once read a book about a group of people who discovered a hidden temple city in a mountain range, where the Incas-the ancient civilisation of Peru- had fled to when the spanish invaded. When this group found the burial chamber of one of the inca high priests, they unleashed a powerful curse upon them all...
A certain patch of forest is well known for causing anyone who ventures into it to suddenly go blind. Once they leave the area their vision returns. Rumors of treasure hidden within.