Xul Solar was an artist of alternate worlds, inventor of languages, and dreamer of utopias.

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

The remains of an entire Roman city can be explored in this interactive museum.

A massive work of modern art that appears to be a crop circle in the middle of the desert.

A Spanish town built into the cliffs.

The Avenue of Mausolea is a series of grand palatial tombs.

Ozymandias’ time-keeping temple.

An abandoned saucer-shaped monument in the Bulgarian mountains.

A flooded Mexican cave that hides a river beneath the water.

The ruins of an ancient island city built atop a coral reef in the South Pacific are spectacular and strange enough to have inspired H.P. Lovecraft.

The remains of what was, not so long ago, the world's largest city.

An ancient city exhumed from the depths of the ocean.

The once great capital of Egypt now crumbles forward as evocative ruins.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

Nazca pilgrimage site covering 370 acres is a popular stop for archeologists and looters.

A set of ancient drawings in the desert of Peru that are so massive, many of them can only be fully seen from the sky.

A clock designed to run with perfect accuracy for 10,000 years.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

A battle between nature and architecture in the Cambodian jungle.

The enigmatic and seldom visited ruins of a Mayan city-state.

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

These azure waters were thought to lead to the Mayan Underworld.

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

Abandoned city hidden from the world by tropical forest and isolation on the coast of Kenya.