The ruins of a medieval castle that once belonged to one of the most powerful families in the Netherlands.

Crouch down, stretch tall, and be sure to flail your legs to pay homage to the Monty Python classic.

This bird-loving brewery is situated in an old municipal bathhouse, nestled beside a 300-year-old windmill.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

The attic of a four-century-old canal house hides a clandestine church.

Inspired by "The Starry Night" this Dutch bike path turns into a glowing work of art each night.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

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

The verdant mossy ruins of a Franciscan monastery lie in the remote Sintra hills awaiting exploration.

The sinister ruins of one of the worst dam failures of the 20th century lie in this astonishing alpine setting.

This sublime architectural marvel is a rare example of an expressionist church.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Rippling sand dunes frozen in the Arizona rock.

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

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

The tallest waterfall in the Netherlands is a lovely, stepped feature that is only 50 feet tall.

A monument hidden in the woods built in 1938 as a getaway for a Dutch museum curator.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

Houses are tucked between, on, and underneath giant boulders.

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

This unattributed sculpture in Amsterdam is hiding in plain sight.

Built by crowdsourcing, this wooden foot bridge saved a part of Rotterdam that was languishing in wait of city funding.

The world's largest wooden structure.