Most of the world's holiest places sit in plain sight, able to be seen and experienced. But there are some hidden deep underground. The revered tomb of Jesus Christ, a secret Knights Templar tunnel, and a prehistoric temple in Malta with mystical properties--why were they concealed? And what mysteries have we unearthed in these subterranean sacred spaces?

Ancient cultures around the world have aroused fascination, and provoked fear with curses and objects used to conjure them like rings, tablets, and stones. But is there proof that some might have actually worked?