A Christian monastery stands on what was once a holy Incan temple.

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.

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

In this breathtaking canyon, crocodiles bask on boulders and glide through the murky waters.

The masses at this church incorporate enough moonshine and animal sacrifice that they are no longer recognizably Catholic.

Dating back to the second century, vestiges of prehispanic mural paintings are found in this underground palace.

This foreboding building was the headquarters of the terrifying Spanish Inquisition in Mexico.

A trompe l'oeil mural remembers the original colonial building that once stood here.

These spectacular, symbolic serpents lie within the shadow of the Great Temple.

This museum houses two of Mexico's most impressive Aztec monoliths.

A disquieting Aztec sculpture displays hundreds of stone skulls representing the victims of human sacrifice.

Its most enigmatic sculpture is a giantess with a ghostly face on her knee.

This bridge over the River Cuale leads to a neighborhood that was once an escape for Hollywood's elite.

A Lovecraftian altar of nightmarish bronze chairs sits ominously on a boardwalk in Puerto Vallarta.

Never actually a tree at all, this spot was the site of London's public hangings for nearly 600 years.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

A commemorative plaque at the door pays tribute to an "American Patriot" known for his betrayal.

Originally meant to hold a statue of King William IV, this support sat empty for years. Today, it hosts a rotating cast of public artwork.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

An alchemist's “magic door” stands in the middle of a Roman park.

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

The world's largest frame offers spectacular views of the city's past and present.

This futuristic building is yet another architectural wonder in Dubai.