A settlement in Argentina destroyed by floods, a town in the US that has been erased, and a Soviet dream-town that turned into a nuclear nightmare.

Projects include a maze of tunnels filled with haunting remains beneath the streets of Paris and a strange formation of domed structures hovering over the waters off Florida.

A town in West Virginia that fell victim to the pace of change when steam trains became obsolete and an underground complex in Italy that had been abandoned for nearly 2,000 years.

A formerly luxurious and strategic mountain-top villa on the island of Rhodes in the Mediterranean that's been ravaged by acts of revenge by locals since 1955.

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.

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.

A pioneering complex marked by both glory and tragedy that's soon to be lost forever, and towering remains from an industrial age.

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

A secretive underground base that concealed the power to destroy nations, and a sprawling industrial relic clinging to the edge of an unforgiving waterfall.

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.

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 American prison for the violent and deranged with links to an infamous cult leader, and a cavernous tunnel network in France offering shelter from unrelenting bombardment.

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.

Examining a ghost island once belonging to a secretive country on the fringes of Europe. Also, a haunting site in the UK with evidence of strange burial practices.

Within a dense Polish woodland sits a forgotten complex with an explosive history. Also, grand coastal defences in Ghana reveal a tortured past.

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

A real-life concrete jungle in America's 'Rust Belt', and an industrial facility that brought energy to a remote corner of the world.

Eerie ruins hiding in the forested hills of Arkansas, USA, and a disintegrating gulag in Albania that housed enemies of the state.

A volcanic island just off Taiwan containing chilling ruins from its darkest era, and a miniature railway that lies forgotten in the woods of Arkansas.

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.

The home of an African dictator and a sporting hero, and the facility that held apartheid's greatest critic are abandoned, but still have unique stories to tell.

Exploring a jungle refuge concealing a story of royal deceit, nuclear bunkers infiltrated by outsiders, and a haunted hospital marked by scandal.

Exploring a beachside resort with ties to the Russian mafia, a windswept base hiding lifesaving technology, and a site in Iowa plagued by its past.

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.