Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

The world's first commercial spaceport is a disappointment of cosmic proportions.

What was meant to be a temporary exhibit is now a permanent fixture at the St. Louis Zoo filled with beautiful birds.

Speak to a companion on the other side of the room loud and clear through this architectural anomaly.

What was once a presidential estate is now an exotic menagerie and home to the Budweiser Clydesdales.

Less a museum than a bizarre fantasy world created by artists and engineers.

A desert settlement founded and later abandoned by Hawaiian members of the Church of Jesus Christ of Latter-day Saints in Utah's Skull Valley.

This Old West prison built into the side of a cliff was said to be inescapable.

Since World War II people have been decorating this stretch of the Yuma desert with signatures arranged out of rocks.

This ancient trail has claimed the lives of over 2,000 people.

On a small Puerto Rican island, banks of secret naval bunkers lie abandoned and filled with piles of office equipment.

This small primate research island is teeming with playing, fighting wild monkeys.

This bleach-white graveyard overlooking the ocean is accessed through a tunnel.

Legend tells how a Spanish soldier disappeared from this isolated sentry box without a trace.

This chapel on a cliff is renowned for its healing powers and was founded on the site of a supposed divine intervention.

This small fort played a huge role defending Puerto Rico’s capital city.

The bat-covered home of one of the world's most popular brands of rum is located on a tropical Art Deco campus.

This 20th-century mansion plays a key role in one of Puerto Rico's greatest novels.

This former sugarcane transport tunnel is now a portal to a lovely beach.

This giant bronze image of Christopher Columbus embarked on a voyage of its own.

This limestone cave offers an incredible view of the Río Grande de Arecibo valley.

This niche museum devoted to ancient religious artifacts is shaped like the very thing it displays.

The highest peak in Puerto Rico is home to a rare fern that can only be found on six trees at its summit.

This ''hidden'' 19th-century bridge played a simple, yet important role during the Spanish-American War.