The 3.8 billion-year-old rock proves that tectonic plates may have been shifting longer than we thought.

An alien landscape on the banks of the Aegean Sea.

The oldest olive tree in Greece has been bearing fruit for at least 2,000 years.

This town named for the ancient God of War is home to fewer than a thousand people, but it's the birthplace of the Greek Revolution.

Replicas of Apollo's leonine stone guard cats still line a sacred row in Greece.

Temple complex that once housed the famous statue of Nike.

Thousands of rusting train cars have been slowly falling apart on the edge of Greece's second largest city.

Cave on extinct volcano, once home to famous mathematician Pythagoras.

This remarkable cave was discovered after a shepherd watched bees enter and exit through a small fissure.

These ruins in Volvi were once at the intersection of the Eastern and Western Worlds.

Seventeen oak trees sprout from the roof and walls of this tiny chapel without any visual evidence of roots.

A cave network located at the southernmost tip of mainland Greece was once believed to be an entrance to Hades.

The curious underground history of keeping Paris clean.

A majestic lion statue guards this Parisian botanical garden, and feeds on an unsettling item.

Science fiction's grandfather has a fittingly marvelous tomb.

One of the greatest maze designer’s greatest mazes.

This Danish park has celebrated the American independence day since 1912.

Denmark's famous pseudo-hill.

The oldest garden in Prague, once part of an medieval orchard.

Dedicated to the unsung history of human waste.

This doorless 20th-century elevator doesn't stop or slow down.

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

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

According to myth, Zeus himself was hidden in this cave to escape being eaten by his dad.