These faux-cliff dwellings allow visitors to climb around on a replica archaeological site.

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.

These giant mummies are set ominously into a Peruvian cliffside and topped with real human skulls.

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

A mysterious pre-Incan ruin believed to have miraculous healing powers.

These delicate ruins need more tourists to keep them from fading away.

An elaborate Mayan city shrouded in alien conspiracy revealed the tomb of Pacal the Great.

The ruins of an ancient Mayan city, beautifully preserved and only accessible by boat.

The stones of this Incan wall complex fit together so well you couldn't fit a piece of paper between some of them.

A hidden treasure of an abandoned city lies deep in the jungles of Campeche, Mexico.

The largest burial mound in the United States holds the remains of prehistoric West Virginians.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

This one-of-a-kind archeological site is home to strange prehistoric ruins, the original use of which is still a mystery.

Ecuador's largest Incan ruins show evidence of sophisticated irrigation and diplomacy among the ancient builders.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

A devastated ruin in the south of Belize where British explorers claimed to unearth the Mitchell-Hedges Crystal Skull.

The largest Neolithic ruins in the world hide a notably clean prehistoric metropolis.