No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

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

An ancient Egyptian temple in the middle of Madrid, Spain.

One of the world's largest murals covers a large swath of homes in its hillside neighborhood.

This church, buried halfway in lava rock, is all that remains of a Mexican village destroyed by a volcano.

This beautifully deceptive waterfall is something far different from what it appears to be.

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

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

Hidden deep in the Guatemalan jungle is a turquoise paradise of natural pools, caves, and waterfalls.

The crumbling remains of a once-grand building.

The youngest volcano in Central America.

A public display of random paleontology.

This colorful artistic feature atop a Danish art gallery allows visitors to stroll through a rainbow.

Go surfing on this urban wave, "hacked" by local surfers.

Golden cobblestones remember a time when this small alley was used to avoid having to give a Nazi salute.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

Amsterdam's former hotspot for public executions and dissections.

A public urinal so pretty, it was declared a national monument.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

This modest marker near Notre Dame identifies the very center of Paris.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.