Man-made cave with enigmatic carvings, some say made by the Knights Templar themselves.

Hideout of thieves, monks, and goat-footed gods.

Norway's oldest cathedral still in use.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

Europe's second largest ossuary wasn't discovered until 2001.

An underground mansion with fruit-bearing trees and grapes growing beneath the surface of central California.

A walk through the historic city center, under the streets of Seattle.

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.

Temple complex that once housed the famous statue of Nike.

A marvel of Byzantine engineering under the streets of Istanbul.

An underground city of salt.

Protecting the dead from opportunistic body snatchers.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

A plaque at the lighthouse where Frederick Valentich made his last radio contact before he vanished without a trace.

The Dalai Lama named this New Zealand landscape the "Spiritual Center of the Universe."

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

The site where Poe "in great distress, and ... in need of immediate assistance" likely died.

The Boston square dedicated to the dark poet who was born nearby.

Final resting place of one of the classic authors of horror literature.

Guarded by the Angel of Grief, the Stanford family tomb attracts an odd mix of halloween revelry and somber contemplation.

Baroque celebration of the end of the Great Plague of Vienna.

An extraordinary final resting place full of oversized art, amazing statues, and dead celebrities.

Site of the 1889 murder-suicide of crown prince Rudolf and his lover Mary Vetsera.