An enormous steel waterfall is a nod to the substance that shaped Britain's Steel City.

This abandoned Belgian fortress is purposefully being left to nature.

A marble Lucifer hides behind the pulpit of this Gothic cathedral.

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

Part modern art project, part traditional chapel, this see-through church is only substantial from the right angle.

This 19th-century zoological collection has withstood the test of time.

A monumental toilet that is also host to rare plants.

An installation that makes understanding the size of the universe a walk in the park.

A whimsical bridge uses saxophones to pay tribute to two great men and the European Union.

Though they might seem like arbitrary scratches in the wall, these were once official measures of length.

An unsettling sculpture of a boy hanging out in a street in Ghent has been baffling visitors for years.

This narrow Ghent alleyway is an officially sanctioned street art tunnel.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

A Museum of Psychiatry in a still-operating mental institution.

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

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

The historic building has preserved human organs, unusual hexagrams, and scars from a political assassination.

This legendary city has been a tourist attraction for centuries.

A replica of a 17th-century map of the stars stands in the courtyard of a Belgian university.

A 400-year-old church covered floor to ceiling in ex-voto offerings from the faithful.

This small, ingenious cannon once helped regulate Parisian life.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

The construction of this bridge dates back to the 15th century.

Incredible labyrinth of man made caves.