The vast chamber inside this abandoned cooling tower looks like something out of a sci-fi dystopia.

This former hydraulic laboratory is now a woodland dotted with old engineering models.

Abandoned since 1998, this train station has become an oasis for urban explorers.

A beautiful maze marks where three countries meet.

This giant urban staircase was built to keep the city's brave fighting men from getting waylaid in the red light district.

The place where Czar Peter I of Russia resided in 1697 during his Grand Embassy.

This small electronics museum is full of whirring, humming, clicking ephemera.

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

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

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

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

Once the world's biggest telescope, it was later used as a coat hanger by a famous Dutch astronomer.

A lecture hall sink once used by Einstein and other noted physicists is now regarded as a strange science relic.

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

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

Albert Einstein would often sit in this chair during visits to the observatory to discuss science with Willem de Sitter.

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

A once-magnificent collegiate church is falling into ruin.

The Belgian royal family's private depot now stands abandoned and forgotten alongside the tracks.