Twisted buildings adorn the banks of the Rhine river.

This former steel and coal plant is now a neon-lit industrial fantasia.

This "floating railway" is one of the world's oldest monorail systems.

This painted Lego bridge is the product of over a century of locomotive history.

A stunning gilt bronze relief denounced by Hitler as "degenerate art"—even though it was dedicated to the Nazi leader.

Böttcherstraße's bells, extolling Nordic virtues and the great conquerors of the world.

This enormous censer uses a pulley system installed over 400 years ago.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

One of the largest underground systems runs under Canada's largest urban center.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

A decomissioned facility where the German "Transrapid" maglev trains were once tested.

This mine is home to the largest man-made hole in Europe.

A medieval gate once used as a prison and how home to a city museum.

The tallest mountain in mainland Netherlands isn't actually very tall.

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

A late-medieval Dutch castle with trick fountains in its whimsical water gardens.

Building Men of War and Indiamen from Holland's Golden Age.

Take a walk in a recreation of ancient Rome.

An amusement park on the grounds of an unused nuclear power plant, with a swing ride inside the cooling tower.

The struggle of a small Dutch island against the sea.

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

Nestled in the woods lies this land art project: a hybrid between park, maze and natural monument.