An abandoned railroad tunnel is now filled with bioluminescent bugs.

Once an aquarium, this sanctuary now rescues sharks and rays from fishing nets.

At five meters long, that is one big piece of foam poop.

This massive water spout has been luring visitors for hundreds of years, some to their death.

These sea cliffs are an epic natural wonder.

This tree, with its large oval-shaped scar, is a rare piece of Aboriginal cultural history.

These 400 million-year-old caves feature honeycomb limestone formations.

Though it may look like a Modernist cathedral, this structure was built to store massive quantities of grain during World War II.

This ancient rock shelter features cave art and is one of the most culturally important sites in the country.

This abandoned railroad tunnel is now home to a micro-colony of bats and a ghost train.

Australia's largest traditional hedge maze features a Great Gnome Hunt.

This striking royal residence is the largest Renaissance-style castle in Scandinavia.

Walking through this narrow gorge will make you feel like you've fallen into a fairytale landscape.

Considered one of the most haunted places in Europe, this 800-year-old castle was home to noble prisoners.

Along this stretch of beach in Denmark resides several massive bastions of energy.

Europe's official "zero-level," the equator of elevation.

Famed for its pie, this eatery has a hidden tunnel that allowed Catholics to secretly walk to church during the Reformation.

This whimsical statue dumps water on its head to symbolize knowledge flowing into his brain. Or maybe booze.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

The great Danube river starts here.

A German apartment building hosting as many trees as human occupants.