A marvel of Byzantine engineering under the streets of Istanbul.

Upside-down trees serve as natural flower pots in this hanging garden of Alaska.

The walls of these four caverns are filled with art that dates back to the earliest human presence in Europe.

Deep below the dry landscape of Bahia, a cave with intense blue water to float in.

This forgotten chalk mine was reopened thanks to a massive effort from the local community.

Take a dip beneath the stalactites in this amazing cenote.

This geothermal hot spring hides beneath a slowly growing mineral dome.

Three sinkholes filled with warm, crystal-clear water reached by a horse-driven cart on an old train track through the jungle.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

The largest stone moai on Rapa Nui.

Past the hills and beyond the graveyard, this church feels extremely out of place.

Worship at the altar of seafood at this fish-and-chip shop housed inside the town's oldest stone church.

Ruins and statues dot the landscape of this tiny island rich with royal history.

Twisted trees shaped by coastal winds make this woodland look like something from a spooky story.

Rainbow-hued in the summer and crystalline in the winter, this salty lake has inspired battles, temples, and plenty of awe.

China's very own Atlantis is an ornate dynastic city resting at the bottom of a lake.

Two ancient Buddhist temples crown this dramatic rocky pinnacle.

A harrowing trail up a mile-high mountain.

A progressive LGBTQ hub offers dancing, HIV testing, art, and more.

This sensational Chinese temple walks visitors through the 76 weird departments of the afterlife.

Discovered after draining a local pond, these ancient man-made caves are still a complete mystery.