A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

One of seven Jewish catacombs in Rome and one of only two open to the public.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

Venice's "Island of the Mad."

The glowing blue Nymphaeum of Emperor Tiberius.

The underground sanctuary of a mysterious ancient cult.

The angel of death appears to weep black tears at this grave marker.

Isolated atop this Balinese sea crag is a lovely Hindu temple that is said to be guarded by sea snakes.

An alchemist's "magic door" stands in the middle of a Roman park.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

The final resting place of the poets Shelley and Keats.

Ever hear of the Milazzo Cage?

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

Rome's semi-secret peephole vista is also a former Crusader stronghold.