Season 3 - Episode Guide

A mysterious group of rusting ships stranded in an arid desert; a monstrous defensive line on the snow-covered peaks of the Italian Alps; a ghostly collection of ornate buildings deep in the German woodland; the sunken remains of a unique maritime vessel with a story to tell... Once these extraordinary places and objects were at the cutting edge of design and construction, but now they stand disused, sometimes contaminated and sometimes dangerous. But who was it that built these mysterious structures? What secrets do they hold, and why were they abandoned?

An abandoned Soviet prison and forced labour camp submerged beneath the water, the eerie remains of a tunnel leading deep into the heart of Blue Ridge Mountains, strange concrete towers hidden away in Finland's snow-covered countryside, and a colossal rusting relic standing proud on the coast of southern Spain.

In this episode, concrete channels hidden in a mountaintop forest, a collapsing bridge, a marooned military base and the upright rusting carcass of ship - but why have they all been abandoned?

The towering remains of a mountainside structure with an explosive past…a deserted and disintegrating cityscape in the heart of Detroit…a former top-secret Soviet facility still shrouded in mystery off the coast of Estonia…a strange hulking mass of concrete lost in the Polish countryside.

A devastated cliff-top ruin in a pock-marked landscape that helped turn the tide of war, an extraordinary tall ‘tower of death' in the middle of a busy city, an eerie concrete structure stranded at sea that came to a gruesome end, and a mysterious heavy metal monster abandoned in a remote field.

Hidden tunnels that saw a city prosper, a sunken wreck with a remarkable past, a concrete wartime dome and a mysterious cold war building all feature.

A village ruin, a ghostly fleet of ships, a bridge to nowhere hidden in a forest and strange metal structures in a wood all feature.

An eerie, empty country village which hides a sad secret, a mysterious tower battered by the elements and scarred by war, a desolate and forgotten ravaged town decaying in the desert, and a disused railway deep beneath the streets of a city. But why were they abandoned?