Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.

Copenhagen's celebrated theme park and gardens.

A mesmerizing landscape of 18th-century cellars carved out of the land.

A Cold War secret surveillance tower used to spy on radio communications.

An enormous and lavish Gothic church in Czechia.

This renaissance château was home to an infamous witch hunter who sent a hundred suspected witches to their deaths.

Massive installation of Europe's negative stereotypes.

An ornate plague column – built to celebrate life – claimed the lives of numerous artisans during its construction.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

A massive 1830s industrial site once known as Czechia's "Iron Heart" has been transformed into a playground of science, technology, and art.

Underneath the city that invented pilsners are a series of historic tunnels that have been storing beer for centuries.

This unusually shaped mountaintop tower looks like a UFO floating over the city.

This network of conjoined cellars was riddled with traps and supposedly allowed the townspeople to pretend their homes were deserted.

Looming communist pillar with a Czech twist.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

This former quarry is now a picturesque gorge that hides a sunken lake.

A spiral staircase twists to the top of this unusual Czech lookout tower.

Bohemian paradise covered in majestic forests.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

Thirty creepy ghosts now inhabit this decaying 14th-century church.

A museum of alchemy and a basement laboratory all housed in an ancient building in a Gothic tower.

Europe's largest natural bridge has a 19th century royal chateau built into its side.

Walk through Czech history in Prague's largest graveyard.

A Jenga-style cylindrical tower of books that appears to go on forever.