Go inside to really appreciate this 500-year-old technological masterpiece.

Pilgrimage site for star-crossed lovers.

Beyond the usual stories that attend old prisons, this one has deep bloody undercurrents.

Mysterious glowing orbs float through the desert night.

The prototype for all Nazi concentration camps.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

Copenhagen's celebrated theme park and gardens.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

This historic stone bridge has an entire neighborhood clinging to its sides.

This "second" cemetery represents New Orleans' attempt to keep cholera at bay.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Where the lovelorn find a home for their sentimental keepsakes.

This sacred cavern, 400 feet deep, is home to millions of bats and an ancient burial ground.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This one-time health resort was used by aristocrats around the world.

Museum dedicated to the terror regimes of Hungary.

A musical instrument played by the sea.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

A priceless collection of the Nation's cryptologic history.