This ultra-modern wooden boardwalk turns the ocean into a swimming pool.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

A popular swimming hole that hides one of America's most deadly diving spots.

An experimental, automotive replica of Stonehenge.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

Walk in the footsteps of the gods and straddle two tectonic plates.

These mysterious mazes carved on the rock may be up to 4,000 years old.

This modern labyrinth lies in the shadow of a ruined medieval castle.

Garden dedicated to native carnivorous plants and site of huge flytrap heist.

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

The ship that got left behind.

A former reservoir that was only recently discovered after more than 60 years of disuse.

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

Designed as a labyrinth, this subterranean prison was crafted without bars or doors.

This once-popular otherworldly landscape was formed by one of the largest volcanic eruptions in history.

The sculpture is made of more than 100,000 knives collected to raise awareness about violence.

What looks like a crashed Zeppelin is actually a bright, airy reading room perched atop a modern museum.

An artsy hidden staircase leads to breathtaking views of San Francisco.

This seaside Italian village doesn't just look Escher-esque, it actually inspired the mind-bending artist.

Monty Python fans will recognize this abandoned mine as the Cave of the Killer Rabbit of Caerbannog.

Amalfi's pre-industrial history is slowly being engulfed by the lush vegetation of the Ferriere Valley.