This ancient structure is widely thought to be the oldest intact pyramid in the world.

The underground sanctuary of a mysterious ancient cult.

Rebuilt remains of a temple to Roman god Mithras.

This 19th century cyclorama acts like an analogue time machine to a different era.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

A 1:20 scale piece of the Netherlands commissioned by a queen lets visitors take a stroll as giants.

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

Pull up and have a drink at a museum filled with hundreds of years' worth of shipwreck artifacts.

The birthplace of most all of Europe's space missions is here on the Dutch coast.

This imposing tower named after the mythical sword of King Arthur is considered the tallest freestanding climbing wall in the world.

This unattributed sculpture in Amsterdam is hiding in plain sight.

A historic observatory now an astronomy museum beautifully situated at the moat of the Middle Age city centre.

This enormous storm barrier is one of the largest moving structures on Earth, with each arm taller than the Washington Monument.

An awe-inspiring giant blue whale jaw bone stands in the center of this Dutch island.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

The 20-mile causeway that separates the Netherlands from the sea.

This disused VLF radio station is no longer in service but the surrounding town still bears its name.

This giant radio telescope would be a rusting ruin if it hadn't become such a beloved relic.

A Netherlands hotel where you can sleep inside a wine barrel.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

The unbelievably opulent home built for an infamous newspaperman.

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

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.