This cave holds a surprisingly colorful variety of geological oddities.

Ancient pueblos built into the base of a natural canyon wall.

A fantastic castle rumored to be the birthplace of King Arthur.

The stately remains of Llywelyn the Great's mighty fortress.

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

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

A theater sits abandoned on Roosevelt Road, once majestic in splendor, now majestic in decay.

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

A fitting attraction for the corn capital of the world.

Mysterious 500-year-old tapestries depict a unicorn hunt.

A curious sculpture garden and museum in Cochrane, Wisconsin.

An artsy hidden staircase leads to breathtaking views of San Francisco.

On a quiet suburban street stands a peculiarly decorated house covered in mosaics.

A museum celebrating the self-taught artist-environment builder.

A tribute to one granddaughter's old apartment which now represents the whims of each visitor.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

An unreal vintage shop that wears its dadaist influence on its zombie fish.

An oddly poignant roadside attraction celebrating American folklore.

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

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

A preserve with 75,000 ancient drawings remains the realm of public – not just scientific – exploration.

A museum dedicated to the alleged Roswell Incident.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

A historic freight system that found the true gold rush is in tourism.