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

Europe's largest natural bridge has a 19th century royal chateau built into its side.

Formerly secret, precariously perched boulders.

This isthmus in the Bahamas narrowly separates the roiling Atlantic from the cool Bight of Eleuthera.

This Sumatran root bridge took almost 30 years to knit itself together.

One man's dream has turned into this naturally growing chapel made of almost nothing but trees.

A spectacular cave and a beguiling lake.

Over the centuries, this island paradise has done it all, from providing monks with ecclesiastical respite to sheltering an exiled Leon Trotsky.

This 16th-century monastery has been turned into a surrealist architecture compound.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

A marvel of Byzantine engineering under the streets of Istanbul.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

Too much gossip or just missing curfew could land you in here for a couple of days.

An industrial site turned into Hungary's most cherished natural wonder.

The glowing blue Nymphaeum of Emperor Tiberius.

This vast, water-filled underground labyrinth can only be toured by boat.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

One of the world's tallest waterfalls wasn't revealed to the world at large until 2006.

The top of society once luxuriated in this world-class hotel, which continues to impress, even in ruin.

A naturally beautiful, seemingly bottomless deep blue spring.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

The gutted remains of this Estonian mansion are a monument to a tragic love.

Bad farming practices caused this unnatural natural wonder.