The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

Giant works of art interspersed throughout meadows and woodlands offer a new discovery at every turn.

A magnificent church designed by world-renowned architect, Frank Lloyd Wright.

One man's unrequited love stands in a glass box forever.

This otherworldly church spire reaches up toward the heavens.

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

This giant green head remembers one of America's jazz giants.

University City's quirkiest resident lives in a park named after its first.

A sculpture of a giant man escaping from the depths of the Earth.

A subterranean haunt where wine and homemade biscottis are always on the menu.

Entombed in this strange, white stone hill are the deadly remains of radioactive weapons production.

The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

Once an ambitious nature spa, these forest ruins now provide a serene monument to failure.

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

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

This small plaza encourages people diagnosed with cancer to never give up hope.

A 30-foot stack of piano keys memorializes one of the greatest keys players in jazz history.

All that remains of a gigantic earth-moving machine.

A circle of giant painted vases in the former pottery capital of the United States.

A monument to a Native American leader who was known for never breaking a promise and met his end after signing a deal with white settlers.

Inside, ancient treasures. Outside, modern contradictions.

Funded by John D. Rockefeller, this is one of the earliest, and most beautiful, shopping arcades in America.