Railways may have forged this quintet of lovely tunnels, but now they are open to hikers.

World's oldest operating science fiction and fantasy club, once home to Ray Bradbury and L. Ron Hubbard.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

Iceland's "Smoky Valley" is a beautiful river that is shrouded in a constant cover of steam clouds.

The true age of this ancient stone circle is unknown, but its stunning vista isn't in question.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

A gargantuan crystal kingdom.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

Dig for your own trilobites in this goldmine of invertebrates.

Tour the world's largest deep-hole dimension granite quarry, where you can view the plant where gravestones are made and roll a ball down the outdoor granite bowling alley.

This 1920s Dutch barge is now a floating bookstore.

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

The ruins of this antebellum sugar plantation are the end result of a Seminole attack during the Florida Wars of 1836.

The television series' iconic giant foot was borrowed from this classical painting.

A storybook European village in Berkeley.

Frida Kahlo's childhood home, now a museum of her life and works.

A massive cave complex boasts some of the clearest water (and most charming bats) in the world.

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

A futuristic temple of light uses prisms and rainbows to create an atmosphere of peace.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

A "Titanic" superfan changed his name to Jack and set up this strange shrine to the blockbuster, complete with Korean food and Tarot readings.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

Visit this playground of waterfalls, caves and sinkholes.

A unique waterfall that some believe attracts the fairfolk.