Abandoned 18th century weapons factory in the Aezkoa Valley.

An abandoned tank sits in an empty London lot as a symbolic middle finger to local city planners.

This imposing modern citadel started out as a home renovation project.

This crumbling, graffiti-covered mansion sits tantalizingly within reach of the proletariat who frequent a public park.

Abandoned railway line circling the city of Paris.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

This Parisian café sticks almost exclusively to an ethos of reuse.

Overlooking a Scottish loch, this beautifully crumbling castle once inspired a poem by William Wordsworth.

This former Nazi castle was built as a school to train what would have been the future of the Third Reich.

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

A flooded Mexican cave that hides a river beneath the water.

A miniature train-ride through Slovenia's largest cave system.

A musical instrument played by the sea.

This mysterious and once-grand memorial still embodies a remarkable architectural vision.

Ruins of a German Castle on top of a towering stone pillar.

Massive installation of Europe's negative stereotypes.

Bohemian paradise covered in majestic forests.

Two monstrous faces loom over a village in Czechia.

Increasingly decayed figures stand as a powerful reminder of the human costs of Czech Communism.

Steadily reminding Czechia of its past.

A saintly relic hidden in a Prague church basement.

This Czech military museum is home to pink tank that was once a symbol of art and political rebellion.