From scholastic to sepulchral - now under reconstruction.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

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

Geothermal waterfalls in Tuscany.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

New York City's smallest piece of private property.

Abandoned 19th century homes once occupied by naval officers, soon to be demolished.

Hear the quietest sound from across the dome.

Ride the subways of yesteryear.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The hallucinogenic center of the ancient world.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

The "world's biggest dinosaur" once housed a creationist museum in its abdomen.

Abandoned railway line circling the city of Paris.

Elevated freight railway turned wildly successful urban park.

The celebrated eyesore created by starry-eyed sweethearts.

The oldest cemetery in New Orleans, resting peacefully for over 200 years now.

Famously misunderstood wonder of the ancient world

The final resting place of New Orleans' most famous voodoo priestess.

A 200-year-old bar in the historic French Quarter refuses to give up its place in history, nor its role in securing ours.

Try not to get slimed in Tribeca.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.