Walk over a 150 year old manhole.

Virgil's many-mouthed gateway to the underworld.

Labor provided by Great Depression-era programs restored these 25,000 acres in Tennessee.

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

Tour the world's largest deep-hole dimension granite quarry, where you can view the plant where gravestones are made and roll a ball down the outdoor granite bowling alley.

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

Remnants of a Victorian garden feature sitting in public woodland.

Mysterious meeting place for UFO hunters near Area 51.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

This cemetery features modernist statues as strange as its name.

Visible below the waves are memorials to the city's Gold Rush dead.

Where the lovelorn find a home for their sentimental keepsakes.

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

The highest dunes in California are the most likely place in the area to hear the Singing Sands.

Where Aleister Crowley taught magick in "La Chambre Des Cauchemars," his "Chamber of Nightmares."

World-famous, Pink's still manages to keep its prized cult fetish status.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

A canvas of crops grow from vibrant red soil in this terraced farmland.

A beautiful maze marks where three countries meet.

A popular tourist cave with a dark past.

Ancient paintings known as the "Sistine Chapel of Cave Art."

Millions of glowing microscopic organisms light up the waters of this luminous lagoon.