Near the destroyed city of Pompeii, an eerie complex of underground tunnels snakes beneath a volcano, and some believe these passages were intended as a gateway to hell. New discoveries reveal exactly why they were built and why they were abandoned.

A strange complex of buildings on a remote tropical island was once home to a large seaside community, but today, locals avoid the area and claim that it's haunted. New discoveries reveal why this eerie place was built and why it was abandoned.