Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

The ruins of an abandoned church mingle with the graves at Oaxaca’s General Cemetery.

Eco-village hidden in the foothills of the Alps that created a massive system of psychedelic underground temples.

This beloved, centuries-old tree stands at the center of a small park dotted with archaeological artifacts.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

Thousands of colorful pirogues showcase ingenious craftsmanship at the largest fishermen port in Nouakchott.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

Sited in an Inner Mongolian desert are the remnants of an important trade stop along the Silk Road.

Unexplained bald patches in the landscape grow and recede over time, as though they are somehow alive.

This curious fresh and salt water lake holds a secret that draws in deep divers from around the world.

Every spring, locals see the shadowy figures of a ghost army of slain Greek soldiers descend upon this ruined fort.

For centuries, this large Roman villa remained hidden thanks to the eruption that buried nearby Pompeii and Herculaneum.

The world's longest outdoor escalator takes visitors to the top of China's largest dam and is also shaped like a dragon.

It’s said this crypt was the setting for the tragic finale of the Shakespeare play.

This floating garden in the sky is straight out of a fairy tale, but the real thing is nothing short of magical.

The world's longest tunnel with an undersea section.

Defying all odds, this lonely little tree found a home on a log sticking out of a Canadian lake.

These Egyptian statues have survived for 3,400 years and were an acoustic wonder of the ancient world.

This Russian religious complex is a Frankenstein's chapel that includes influence from almost all the major faiths.

Two monstrous faces loom over a village in Czechia.

Granny Smiths and Fujis can both be traced back to Kazakhstan, where apples still grow wild.

An enormous, inside-out glass globe built in 1935.

This massive chapel in the middle of the Indonesian forest is both haunting and fowl.

A stone circle on the slopes of a Caribbean volcano commemorates the leader of an anti-slavery uprising.