Possibly the most beautiful carillon in the world, set atop Iron Mountain in Florida.

The 44,000-ton aircraft carrier was purposely sunk to create an artificial reef teeming with life.

The "worst battleship ever built" is enjoying a grand second act, submerged 30 feet in the Gulf of Mexico.

Wading through a small lagoon reveals a secret, wild stretch of pristine beach.

The futuristic test model of an iconoclastic visionary who wanted to redesign the world.

This facility, now a museum, once housed and trained U.S. Army Air Force pilots who flew during the Allied invasion of Normandy.

An aviation relic that made coast-to-coast travel possible.

These mysterious ruins are hidden amid this sleepy coastal city.

The only known working replica of the world's first self-propelled vehicle.

One of the only Florida forts to remain in the hands of the Union all through the Civil War still stands as a historic stronghold.

Though nicknamed the “Russian Freighter,” this ship was actually sunk off the coast of Pensacola by the U.S. government in a top-secret operation.

One of many gator theme parks, abandoned in the sugar fields of South Florida.

A graveyard of bathyspheres and diving bells paints a weirdly accurate account of ocean exploration's rickety history.

The world's largest private aircraft collection.

This state park was once an important Native American cermonial center.

A Florida college boasts the world's largest single-site collection of structures designed by Frank Lloyd Wright.

Part of a highway network meant to connect Miami to Montreal, this 10-mile stretch of road made from red bricks is still around 100 years later.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

The last remaining predreadnought battleship in the world has been a museum for nearly a century.

The remains of a magnificent medieval fortress that was the capital of a vast empire.

A unique collection of diving equipment spanning antiquity to the present day.

This former luxury resort in Kaua'i is now an abandoned relic.

This lovely university observatory continues to sit abandoned since its potential savior was sent to jail for fraud.

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