A Cold War command center is hidden under an idyllic countryside.

The foundations of a forgotten fortress, wedged in between two streams.

Hiding the longest subterranean river known in the world.

A magical and peaceful ruined Cistercian abbey in what is now southern Belgium.

This former Masonic lodge has been transformed into part museum, part bar, all awesome.

This abandoned Belgian fortress is purposefully being left to nature.

Ancient man-made caves underneath small town Belgium.

A museum celebrating the Canadian forces that liberated Belgium from the Nazis replete with battlefield miniatures and multiple Gardens.

A Belgian self-built tower inspired by the Bible and ancient civilizations.

This sprawling Belgian fort was once thought of as impenetrable but now it is simply an abandoned relic.

This historical Netherlands fortress still bears the marks of its single siege.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

This large copper bolt represents the benchmark for measuring sea levels in most of Europe.

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

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

The world's first interactive human body museum also serves as a chair for a giant orange man.

One of the oldest masonic temples in the Netherlands, built in 1757.

It's forbidden to dig within this ancient Roman fort hidden beneath a playground.

A grassy pyramid named after a French battle.

Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

The bridges portrayed on EU currency aren't fictional anymore.

The elegant manor house where Kaiser Wilhelm II lived in exile after World War I.

Take a stroll through the hellish grotesques of Hieronymus Bosch in this elaborate Netherlands church.

The giant scales in this museum can still tell if someone is one of the devil's brides just by weight.