Erected in 1697 this Philadelphia bridge is the oldest surviving roadway bridge and perhaps the oldest stone bridge in the United States.

The abandoned coal loading dock is a canvas for unsanctioned art.

One artist's love letter to his city and its citizens plays out across dozens of bright murals painted on the sides of decrepit buildings.

A surprising museum of 20th-century technology.

A completely round house designed for the Atomic Age.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

These mid-century motels once housed the workers who built the Glen Canyon Dam.

Archaeologists believe this panel of petroglyphs depicting descending sheep and other figures in Glen Canyon are 3,000 to 6,000 years old.

This hidden gem in Arizona is truly worth the rugged journey.

Although now a decaying ruin, this stone cabin's history includes several notable figures.

Cave shrine on Monte Pellegrino.

A madman's personal garden filled with 1,000 sculpted heads.

Tourists to the mountaintop Sicilian town often overlook its ancient fortifications.

Italian cave with exceptional acoustics and an unsavory history.

142 ceramic steps become a mosaic once a year.

"Stairs of the Turks", a chalky white cliff eroded conveniently into stairs, allowing for easy pillaging.

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

These ruins of a Phoenician sanctuary in Sicily have a dark history.

The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

A 16th-century horror show built in a lovely Italian garden.

This mouldering abandoned mental hospital was once a center for progressive healing.

An extra-wide chair built to accommodate the former president's big behind.