Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

A toxic ghost town sitting atop a massive coal fire.

Hellam Township is reputed to feature seven remote gates, which when passed through in the right order, open an entrance to hell.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

The monument marks where Simón Bolívar and his Spanish adversary Pablo Morillo met to have a drink together.

Dr. Farid Mattar's Monument of Peace.

Ruins of the laboratory where a mysterious doctor invented an embalming fluid and stored his mummies.

This former shopping center now acts as the eccentric lair of the Venezuelan secret police and their shadow prison.

This "floating island" plateau sits 7,671 feet above the forest floor.

A town church once nearly submerged by the damming of a river is now hauntingly visible as the water recedes.

This everlasting lightning storm may be the world's largest generator of ozone.

This glacier interpretation center houses the world’s only bar made completely from glacial ice.

This beautiful fountain was sculpted by a female artist who was ahead of her time.

One man's quest to collect artifacts from every aspect of human life has resulted in this eclectic Argentinian museum.

An ancient forest of the Paleocene Age turned to stone.

Mysterious and ancient carved standing stones.

Visit this odd display of indigenous style in Argentine wine country.

A brightly colored natural bridge formed by mineral-rich hot springs high up in the Andes.

Mineral springs believed to hold therapeutic properties draw in visitors from all over.

A toxic lake near a volcanic caldera that is home to flamingos and other life.

A gateway to a mysterious network of underground tunnels.

Stenciled handprints and wall paintings dating back 10,000 years, some of the earliest forms of cave art.