The opulent home that inspired Tintin's Marlinspike Hall and the adventures within.

This castle-fortress is a living example of the transition from medieval defenses to modern fortifications.

Sky ships, planes, and portraits left as unique tokens of hope and thankfulness.

This salt marsh in Southern France is as pink as the flamingos that inhabit it.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

Go inside a revolutionary, cage-less zoo where 70 species of monkeys roam free alongside their human visitors.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

Hiding the longest subterranean river known in the world.

This historic stone gate tower is now just a lonely relic in the middle of a swamp.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

An intricately decorated tiny place of worship.

An odd museum dedicated to French fakes.

The topiary maze at the Habsburg hunting lodge.

The fairy tale castle of the "fairy-tale king."

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Tiny castle in the middle of the Rhine made you pay to pass.

This replica of the Greek structure is in the heart of Nashville.

France's most famous cemetery, with some of its most curious tombs.

One of the largest caves in the world open to the public.

It houses the remains of a 17th-century version of the Titanic.

Metro station with a claim to rock n' roll fame.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

A miniature Italianate fantasy village on the coast of Wales and the set of ITC classic "The Prisoner."