Steaming blood-red hot spring from hell.

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

Experience park where visitors are told to expect the unexpected.

Bioluminescent firefly squid light up this Japanese fishing port.

The oldest hotel in the world has been operated by the same family for over 1,300 years, even catering to samurai.

A strange rock with a sinister reputation lurks within the crimson waters of this Scottish glen.

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

Western Europe's only representation of a Roman goddess still in its original location sits in an unassuming park.

A subterranean playground in an abandoned slate mine.

A metal tree emits eerie, melodic notes on top of Lancashire's Crown Point.

The largest greenhouse in the world is home to over one million types of plants.

Hear the quietest sound from across the dome.

The longest hedge maze in the world.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

These fantastically named natural pools look like something out of a Scottish myth.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

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

A former bastion of Rajput chivalry, this massive hill fort is the site of legend and tragedy.

Hidden in the shadow of a rocky fortress is one concubine’s long-forgotten legacy.

This complex of vertically-excavated Buddhist, Jain, and Hindu monolithic temples in India's Maharashtra providence illustrates a spirit of tolerance characteristic of ancient India.

Centuries-old bridges grown from tangled roots.