A black cat protests the City Guild in Riga's Old Town.

Spend the night in 1920s Latvia in this historic recreation and movie set.

Denmark’s never-ending bridge.

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

This Danish castle is supposedly haunted by a woman too independent to not be a witch.

The decaying remains of a 1960s mechanical wonderland that never officially closed.

This Denmark theme park is part family attraction, part experimental archaeology project.

Nearly 40 miles and 1,000 years of limestone mines under Denmark.

A perfectly circular stronghold constructed in the 10th century is now a nucleus of Viking culture housing a museum, village, and reenactment of an epic Viking battle.

Museum on earth sciences featuring a recreation of a famous curiosity cabinet.

Old Danish castle immortalized in Shakespeare's Hamlet.

This secret collection of the strange and occult was rediscovered in a forgotten room of an old house.

This colorful artistic feature atop a Danish art gallery allows visitors to stroll through a rainbow.

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

A walkable map of the world, made from soil and stone by one man.

Six beautiful wooden giants are hidden around Copenhagen.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

Every part of this unusual home is built into the sandstone rock.

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.

Enormous sandstone towers loom within a Czech forest.

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.

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