Flames have been burning within this mountain for more than 2,500 years.

The hallucinogenic center of the ancient world.

This legendary city has been a tourist attraction for centuries.

This 200-meter-high waterfall marks the site of Achilles’s immortal baptism at the mouth of the River Styx.

Rome's ancient Etruscan rival, now a park full of ruins.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

The underground sanctuary of a mysterious ancient cult.

Roman politician Herodes Atticus built this nymphaeum to honor his wife, whom he may have murdered.

Jesus' footprints and the first catacombs in the world.

A natural gas leak provides a flickering flame beneath a waterfall.

The set location for a 1987 cult classic draws international film buffs to the middle of the Mojave Desert.

Made famous by 'Star Wars,' these troglodyte homes face an uncertain future.

The original movie set for the home of 'Star Wars' hero Luke Skywalker.

No one knows who created the statues or if they are arranged properly—let alone the artwork's real name.

The plague quarantine island home to the alleged "Vampire of Venice."

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

Lie in a hammock where George Washington stood.

Long the exclusive domain of birds and vagabonds, this little-known Central Park peninsula is open to the public once more.

Read a book next to a Midtown waterfall.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

This secluded ruin was once a home for exotic plants.

A miniature rainforest is growing inside of a Midtown Manhattan office building.

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

Final resting place of two dozen New York City harbor ships.