A luxuriant botanical garden below sea level.

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

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

Holding multiple historical boats and an entire 19th century village, this New England attraction is the largest maritime museum in the world.

The former home of Samuel Clemens and family remembers the happiest period of the author's life.

These faux-cliff dwellings allow visitors to climb around on a replica archaeological site.

The superstar of Cold War nuclear bunkers has been featured in countless films but is now barely operational.

The highest bridge in America was built for an almost unnervingly small amount of money.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

This lonesome Monterey cypress has survived centuries of wind, salt, and at least one attempt at arson.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

Concrete strongholds stand guard over the Golden Gate.

A battleship’s mast sits atop a turret-like memorial, commemorating those who lost their lives in one of the precipitating events of the Spanish-American War.

The first declared National Monument in the United States.

One of the oldest living oak trees in the Southeast.

The world's longest known cave system.

This black shoreline is made up of exploded lava particles.

Bits and pieces from the ill-fated Donner Party's winter cabins.

An abandoned Jazz Age dream home and con man's hideout in Death Valley.

The awe-inspiring ship from the golden era of cruising has an incomparable history and a reputation as one of the world’s most haunted places.

The unbelievably opulent home built for an infamous newspaperman.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

This scenic Maryland park was the site of one of the worst prison camps of the Civil War.