The world's largest man-made underground caverns offer unparalleled underwater wonders.

This wooded grove of beautiful hand-built stone grottos is a hidden gem within a shuttered Franciscan monastery.

The final remnant of the Arkansas zinc industry is this historically protected ghost town.

This museum located in the "Corn Cob Pipe Capital of the World," chronicles the history of cob pipe.

The Quapaw tribe supplies the meat and produce in this Oklahoma casino restaurant.

Twenty-year effort to raise a castle using tools and techniques from the 13th century is now abandoned in the Arkansas woods.

A rare example of a medieval house in Rome adorned with a melancholic inscription.

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

A tribute to Ponce de Leon's supposed quest for eternal youth.

This beautiful Miami garden was designed as a laboratory for tropical plants.

Neglected resting place of some of the city's early luminaries—and a woman encased in concrete.

Built in just a little over a week this preserved bunker was created to protect our most attractive POTUS while he was on vacation.

The oldest house of worship in Palm Beach has a wonderful tropical garden.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

When you can't get to the Pacific, just go to Florida.

Japanese gardens dedicated to the Japanese farmer that refused to throw in the trowel.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

A high-octane shrine to the greatest Texans who ever lived.

Hidden within a Gulf Coast port city is a wonderfully eclectic museum whose beginnings were housed in a bank window.

Baptisms in troughs and post-sermon rodeos at the world's biggest cowboy church.

Inmates dig the graves at the largest prison cemetery in the U.S., the final resting place of both cowboys and Indians.

No one is sure why this mysterious tradition started.

The wood bears a hidden love note carved by a young Johnny Cash.