A factory director designed what was the world's longest suspension footbridge in 1923 so his employees could get to work safely.

A domed disco abandoned since the '70s now attracts artists and explorers under its unique roof.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

A miniature train-ride through Slovenia's largest cave system.

A unique form of erosion created an uncanny landscape of boulders perched atop slender columns of clay.

A massive mausoleum towers over the gravestones in a 19th-century Italian "model village."

A climbing route in the mountains of Italy’s Dolomites, built for soldiers during World War I.

These delicate sand pyramids look like naturally occurring gothic spires.

An open-air museum in a mountain valley features works designed to blend in with—and disintegrate back into—their natural surroundings.

The highest waterfall in Italy is only "turned on" five times a year.

This spire on an Austrian mountain is wrapped around a long spiral slide and has the world's tallest wooden observation deck.

The summer tourists on these cliffs are thousands of seabirds.

The oldest steel ship in Iceland has been beached for years and is now a rusting ruin.

These concrete domes were installed on an Icelandic bluff to honor a very specific musical tradion.

Two volcanic lakes in an enormous crater formed in a prehistoric eruption.

This replica Viking village was created for a film that was never shot and is now open to visitors.

This hobbit-y little hot spring may be the oldest spring used by humans in all of Iceland.

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

This modern monument to pagan belief looks like it was transported straight from ancient times.

These ominous lava formations were said to be an entrance to the netherworld so of course they inspired a famous metal band.

A winding, blood-red tunnel of hardened lava navigable by foot.

The most powerful waterfall in all of Europe.

Iceland's "Smoky Valley" is a beautiful river that is shrouded in a constant cover of steam clouds.

This elegant arc of a waterfall marks a religious turning point.