This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

This strategic isle was once swapped between empires and almost entirely destroyed in a bomb explosion.

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

The last bastion of Roman presence north of the Alps looms over a German town.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Climb inside an iron crystal magnified 165 billion times its normal size.

A magical and peaceful ruined Cistercian abbey in what is now southern Belgium.

Every summer local children form "pysja patrols" to save young birds that have wandered from their nests.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

The most powerful waterfall in all of Europe.

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

Walk in the footsteps of the gods and straddle two tectonic plates.

Iceland's largest lagoon is home to stunning multi-colored icebergs.

This fantastical waterfall is hidden in a cave located in a cracked cliff.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Rising from the sea like a stone monster.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

Medicinal spa created from the mineral-rich runoff of a geothermal power plant

An ancient capital city that dates back 3,000 years and harbors many surprises.

Gladiators battle and chariots race daily in the ruins of a once-great Roman city.

The most gigantic, swoony, intimidating trio of fingers in all of antiquity.

Home to more than 13,000 pieces of war memorabilia and military equipment.