A fifth-century temple improbably built into the side of a cliff.

These quaint French houses dangle precariously over a precipice.

The small cliffside monastery known as the Tiger's Nest is said to be the meditation site of an 8th-century Buddhist master.

A tiny chapel clings to a precipice above Germany’s gemstone capital.

This centuries-old Italian chapel hangs midway down a sheer cliffside.

A castle perched precariously over the Crimean Sea.

This precariously perched fortress was once ruled by a crow-worshipping baron.

A historic observatory precariously perched at the "Top of Europe."

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

Hidden in the Santa Ynez Mountains off Highway 154, this tiny restaurant once served as a stagecoach stop.

An Ethiopian "Jerusalem" featuring a church hewn out of a single rock.

An otherworldly restaurant perched on the edge of a jagged cliff next to a medieval holy city.

The cathedral of a controversial, conservative, schismatic sect that declared the Catholic Church heretical and founded its own succession of popes.

One of the world's oldest and most massive living organisms is a grove of quaking aspens.

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

Amalfi's pre-industrial history is slowly being engulfed by the lush vegetation of the Ferriere Valley.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

The abandoned funicular tunnel was a secret base for the BBC during World War II.

A thin pane of glass keeps visitors from sliding off this futuristic skywalk.

Longest road tunnel in the world features an air treatment plant and the illusion of daylight.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

Raging waters have created a strange geological site that looks like something off of a progressive rock album cover.

An abandoned faux-pub made famous by a Guinness commercial.