Strange structures rusting away at sea… an abandoned concrete pyramid… a huge machine, forgotten in a field... an empty complex in a city. Who built them? And why were they abandoned?

A technological masterpiece lost to the sea. A mysterious concrete giant. A strange structure built on a river. A marvel in the Arctic. Who built them? And why were they abandoned?

An abandoned Nazi station. A military base in the US Desert. A lost Arctic facility that goes deep. A huge desolate industrial area. Who built them? And why were they abandoned?

A vital lost military facility. A facility in a sprawling desert. Towers in an industrial wasteland. An extraordinary sight high on a mountain. Who built them? And why were they abandoned?

An abandoned concrete wall. Five strange deserted structures. A lost escape route from nuclear Armageddon. A submerged link to D-day. Who built them? And why were they abandoned?

An American symbol lost to the jungle. Concrete monoliths in a European forest. A vast cold war relic. A bizarre structure built to speed trade. Who built them? And why were they abandoned?

An industrial site lost in a forest. An American installation that waged the Cold War. An abandoned tower. A derelict ruin on a sand dune. Who built them? And why were they abandoned?

A highway in the jungle that leads nowhere. A fortress on the edge of the sea. Forgotten bunkers in the Alps. A mysterious manmade island. Who built them, and why were they abandoned?

Rusting ships stranded in a desert; a mountaintop defensive line; a ghostly collection of buildings; sunken remains of a unique vessel. Now they lie disused, contaminated, and dangerous. But who built them? And why were they abandoned?

An abandoned prison beneath the water; a tunnel in the heart of a mountain; concrete towers hidden in the woods; a rusting coastal relic. Now they lie disused, contaminated, and dangerous. But who built them? And why were they abandoned?

Concrete channels hidden in a mountaintop forest; a collapsing bridge; a marooned military base; the upright rusting carcass of a ship. Now they lie disused, contaminated, and dangerous. But who built them? And why were they abandoned?

A towering structure with an explosive past; a deserted cityscape; a mysterious top-secret facility; a vast Nazi construction. Now they lie disused, contaminated and dangerous. But who built them? And why were they abandoned?

A devastated cliff-top ruin; an extraordinary tall tower; a concrete structure stranded at sea; a heavy metal monster in a field. Now they lie disused, contaminated, and dangerous. But who built them? And why were they abandoned?

Hidden tunnels that saw a city prosper; a sunken wreck with a remarkable past; a concrete wartime dome; a mysterious cold war building. Now they lie disused, contaminated, and dangerous. But who built them? And why were they abandoned?

A village ruin, pitted and scarred; a ghostly fleet of ships; a bridge to nowhere hidden in a forest; strange metal structures in woods. Now they lie disused, contaminated, and dangerous. But who built them? And why were they abandoned?

A country village hiding a sad secret; a mysterious tower scarred by war; a town decaying in the desert; a railway deep beneath a city. Now they lie disused, contaminated, and dangerous. But who built them? And why were they abandoned?