This week, find out why Fordlandia Rubber Town, a symbol of the American dream first established by Henry Ford in the 1920s, is now left rotting in the Amazonian rainforest. Also, what secrets do the enormous monoliths scattered across a secret forest complex in Eastern Poland hold? And what secrets does a fortified corridor of death with a Cold war past stretching for miles across Hötensleben, Germany hold? And a bizarre structure in South Western France built to speed trade was once at the forefront of design, now lies disused and abandoned, but why?

In North Wales a secret facility which once manufactured mustard gas and enriched uranium lies in ruins. In Malta is a luxurious quarantine facility, that hides a dark secret.

The Canfranc Railway Station is an elaborate abandoned Nazi railway station built near a town of only 500 people in the Pyrenees in Spain. But why was it built there and what secrets does it hold? Also examined in this episode is the Salton Sea Navy Base in California - a military post in the middle of the desert in the American west, the Kola Superdeep borehole - a wrecked record-holding Arctic facility in Russia that goes deep, deep underground, and a huge tower looming over an industrial area in Belgium. All of these extraordinary places and objects were at the cutting edge of design and construction, but now they stand disused, sometimes contaminated and sometimes dangerous.

What happened to an infamous pirate city in Jamaica? Also, a grim gulag in Croatia and a Louisiana plantation caught up in the aftermath of the American Civil War.

Bizarrely-shaped huts in India, once home to global superstars, are now eerily quiet and neglected, and a shattered compound in Colombia linked to a criminal mastermind.

A dark past explains why the Pölitz Synthetic Fuel Plant in Northern Poland is now a derelict industrial site littered with tunnels, bunkers and huge crumbling concrete structures lost in dense forest. The site was built in 1937 as part of Nazi Germany's drive to become self-sufficient on fuel, but it was no ordinary refinery. It used the latest technology at the time, at great expense, to turn coal into oil. In 1945 an Allied air raid pulverised the plant, severely wounding the German war machine and leaving the site in ruins. Other structures examined in the first episode include the incredible vertical Phoenix Shot Tower in Baltimore, which was built to provide America's own ammunition, the former American spy instillation called Teufelsberg (or "Devil's Mountain") in Berlin which waged the Cold War against the Soviet Union, and the now derelict Rubjerg Knude Lighthouse which was built on Europe's second-fastest moving sand dune in Denmark.

The Georg Thiele was a technological masterpiece, but it is a shipwreck, lost to the sea in a Norwegian Fjord after running aground during a naval battle in WWII. Also in this episode, a mysterious concrete giant which echoes the Communist era atop a mountain peak in Bulgaria, a fantastical structure built in the middle of an American river, and one of the world's first and finest Artic feats of engineering, The Miles Glacier Bridge in Alaska, which, when it was first built in the early 1900s, was known as the Million Dollar Bridge.

A vast snowcovered monster in the icy wilderness of southern Alaska, a ruined super structure that overshadows everything around it in and a landscape of confusing and surprising structures that once represented a bold statement of Spain's plans for the future. Plus, a long, winding formation that was once supposed to help defend Hitler's Third Reich. And in Budapest, Hungary, the stripped skeleton of an industrial relic lies rusting away.

Claustrophobic prison cells that contain a story worthy of international acclaim, and a vast mountainside complex that held the power to change the world.

An extended special featuring a deserted Caribbean city, an American ghost town still burning and an Arctic settlement facing a terrifying future.

A juggernaut of Soviet engineering which was crucial to the international space race. Deserted Scottish coastal defences and a complex that's crucial to American history.

Exploring a ghost town in Colorado, the remnants of an industrial enterprise in Puerto Rico, and a remote village on Cyprus.

A sprawling Wild West ghost town sits peaceful and abandoned in Montana, USA, but is still haunted by tales of murder, corruption and buried treasure. Also, a cold, dark, underground mountain network that cost the lives of thousands... the crumbling ruins of an English industry that turned poison into profit... a peaceful village that was shattered by the terrors of war.

Including an exploration of a marooned iron-clad structure in Portland, off the coast of England, that hides a dramatic story of war and resilience; Pratt Cotton Gin Mill, a vast facility in the heart of America's deep south that helped tear apart a nation; and a Mediterranean island fortress at Spinalonga, Greece, that became the scene of a dark conspiracy.

A strange group of rusting structures off the coast of England, a dilapidated mediaeval-style castle in the heart of urban America and one of the biggest machines ever built lying forgotten in a German field. 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 incredible stories surround them? What secrets do they hold? And why were they abandoned? Seven huge steel boxes rise 80-feet out of the water off the coast of England at the mouth of the River Thames. Now rusting and derelict, The Red Sands Sea Fort was originally built as a first line of defence to deter the Nazi threat to London. Successfully helping the Allies to victory in 1945, the project is one of the most extraordinary engineering successes of World War II. Also in this episode, a sinister-looking deserted Cold War concrete pyramid in North Dakota; a vast empty complex located in the heart of a Philadelphia; and a 4,000-tonne corroding mass of steel, left to rot in a field in Eastern Germany.

A strange-looking deserted town with an almost supernatural atmosphere on a remote Norwegian archipelago in the Arctic Ocean was in fact an ambitious Soviet mining outpost with a tragic history. Also, a collection of imposing buildings on the southern tip of Australia, the remains of curious-looking basins emerging from the waves in the shadow of the Golden Gate Bridge and the ruins of a monumental construction project in southern Germany that was a ruthless regime's deadly prototype.

Including an exploration of forgotten relics from the defence of America's homeland, at Fort Jackson, USA, concealed by the banks of the Mississippi River; a concrete behemoth at Lorient Sub Base, on the coast of France, that proved invulnerable to enemy bombardment; and a ghostly ruin at Gwrych that is now home to a haunting presence.

An Albanian village home to Allied secret agents, devastated for resisting the Nazi war machine, and a notorious asylum in America that enforced lobotomies on a terrifying scale.

The mysterious Cachtice Castle home to Elizabeth Bathory, said to have killed over 600 girls and a mysterious structure on the 38th parallel.

Ruins of a vast industrial ghost town in the United States, a windswept Scottish island and the remains of a resort in Japan that watched a city burn.

A fairy-tale castle that staged one of the strangest stories of the Second World War and a haunting complex on an old American Frontier.

Exploring a bloody battleground on the Pacific Island of Peleliu and an ominous military stronghold in Russia.

This episode travels to Chile, the Maltese capital Valleta, Havana and Germany, to reveal: honeymoon home of a young princess that offered her a glimpse of freedom; grand monuments designed by the most notorious dictator of the twentieth century; a sprawling industrial complex?the site of a ruthless disappearance; and?the artistic dream of?a revolutionary now in?ruins.

Hear how a crumbling hill in the Peak District and dunes in California caused the closure of two roads. Learn why a route used by the French Resistance shut in 2003.

An abandoned concrete wall... five strange deserted structures. A lost escape route from nuclear Armageddon... A submerged link to D-day... Once they were at the cutting edge of design and construction, now they lie disused, contaminated and dangerous. But who built them? And why were they abandoned?