This spa theme park lets its guests take a dip in pools of coffee, wine, or ramen broth.

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

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

Tubing through a cave lit with glowworms is a magical underground experience.

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

Spend the night in this formerly abandoned traditional Scottish village.

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

Catacombs turned marketplace.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

Famously misunderstood wonder of the ancient world

Hollowed out cedar log tubs set in an ancient towering forest.

A slice of central Asia in the middle of Berlin.

Where manatees are the snowbird vacationers in these balmy Florida springs.

The sign at the garden gate reads: "These Plants Can Kill."

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

Started as a kitchen garden, now the second largest botanical garden in the world.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.