The world's longest known cave system.

More than 5,000 contemporary and "historic" mustards from around the world.

Thanks to a quirk of elevation this gift shop produces magic doughnuts that are found nowhere else on Earth.

A building so large that it has its own weather.

Welcome to old Florida, where a 1940s mermaid show is still enchanting visitors.

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

The largest source of fossilized insects anywhere.

The final resting place of American icon Buffalo Bill, and a museum that aids in telling his tale.

The highest paved road in North America winds its way up Mount Blue Sky in Colorado to an altitude of 14,130 feet above sea level.

Famous church recognized for both its unique design and disciplined monks that live according to the Benedictine discipline.

Curious cave that stays a cool 56 degrees all year long.

European castle ruins in an American state park are actually the product of death and grief.

Self-built house and sculpture park where the creator can still be seen in a glass coffin.

Over 80,000 carved wood blocks make up one of the world's oldest intact Buddhist canons.

This complex of vertically-excavated Buddhist, Jain, and Hindu monolithic temples in India's Maharashtra providence illustrates a spirit of tolerance characteristic of ancient India.

Half-size replica of the Taj Mahal.

Rock-cut cave complex filled with ancient Buddhist artwork.