A unique underground structure dating back to the 1st century BC.

Two gravestones clasp hands over the religious divide.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

Flowers have mysteriously appeared on her effigy every day for the last 150 years.

Artfully arranged bones of 5,800 Austrians.

This network of conjoined cellars was riddled with traps and supposedly allowed the townspeople to pretend their homes were deserted.

More than 100 monumental tombs carved into rock are preserved at this ancient Nabataean site in the Arabian Desert.

Dozens of snakes are housed and worshipped within the walls of this Vodun temple.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Mosaics, storks, and brothels—this ancient city has it all.

This triumphal arch is the only fully standing structure that remains from Roman-era Oea.

A beautiful oasis town dating back to the Roman period still serves as reprieve from the brutal summer sun in Libya.

Magnificent Roman ruins lie vulnerable to destruction on the edge of the Mediterranean.

Dedicated to an "Unknown Man," this grave holds either the remains of a lovelorn suicide or a Cold War spy.

Known locally as the Jungfrutornet, this Medieval tower hides a dark legend.

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.

Las Vegas's very own 40-foot-tall fire-spewing praying mantis.

A collection of haunted objects and macabre oddities under one roof.

A "miracle" that seems to produce more holy fistfights than holy revelations.

This small museum located under the famous cube houses, is home to some 30,000 chess pieces.

Overlooking the spot where the Pilgrims boarded the Mayflower stands Devon's answer to the Colossus of Rhodes.

This salt marsh in Southern France is as pink as the flamingos that inhabit it.

According to a satirical conspiracy theory that persists today, this German city of 300,000 is a hoax invented by the CIA.

The town of Argleton has a postal code and appears on maps and even real estate listings, yet it does not exist.