The tiny, studious rodents greet visitors to the National Archives of Finland.

A half-buried vehicle in Prague's is the latest iteration in a long-running piece by Czech artist David Černý.

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

The mystery of the Putim Ossuary involves a tricorn hat.

Mysterious painted skulls in Moravia.

Bohemian paradise covered in majestic forests.

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.

Two monstrous faces loom over a village in Czechia.

Europe's second largest ossuary wasn't discovered until 2001.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

The headquarters in Salem doubles as an occult art gallery.

The unedited photograph called "Bliss" has graced the screens of over a billion computers.

Monty Python fans will recognize this abandoned mine as the Cave of the Killer Rabbit of Caerbannog.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

A cemetery with goat-horn bedecked gravestones.

This massive subterranean fissure is known as the "underground Grand Canyon."

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.

Sandstone rock formations that look like they belong on the cover of a progressive rock album.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

Colorado's only true geyser is hidden within the San Juan National Forest.

An Ancestral Puebloan ruin that appears to burst into flames in the sunlight.