As the Soviet Army pushes the Nazis out of Poland, they discover a massive city of over a thousand buildings covering ten square miles that was unknown to the Allies, and using the latest science, experts reveal how Hitler was able to keep this sinister place hidden for so long. D.A.G. Fabrik Bromberg was a secret German explosives factory hidden in the Bydgoszcz Forest, providing a third of the munitions for Eastern Front.

Guided missiles, the Wasserfall, and the war-changing V2 were dreamed up and tested in Peenemunde, a German seaside city suddenly overtaken by Nazi elite.

Hidden in a remote mountainous forest is a structure nicknamed the Fly Trap or Hitler's Stonehenge. Researchers still have no definitive idea what it is.

Allied forces stumble across a sprawling complex in the French countryside. What did the Nazis have planned for this mysterious Nazi stronghold?

Why did the Nazis fight tooth and nail to protect the city of Luban? Abandoned factories, hidden tunnels, and strange rumors provide clues to the mystery.

In Poland lies a forgotten Nazi complex which could have sheltered up to 27,244 people from Allied bombs, the purpose of which largely remains a mystery.

Outside the town of Politz lie the ruins of what was once one of Germany's most important assets - a place that kept the German war machine moving.

In 1933, Heinrich Himmler signed a 100-year lease for Wewelsburg castle in Büren, Germany. The space became a clandestine training space for the SS.

A chilling discovery in the furthest reaches of Eastern Canada hints at the true depths of the Nazis' seafaring capabilities.

Scientists in Kamienna Gora work to keep the Luftwaffe flying but are they also building Hitler's next revenge weapon?

A vast network of Nazi bunkers buried in the Hague tells the story of the greatest battle of WWII that never was.

Where are the missing billions? Exploring the tunnels, lakes, and secret caches used by the Nazis to hide spoils of war.

An abandoned eerie structure in France could have doomed the Allies in World War II, and new discoveries at this mysterious site reveal the truth behind top-secret Nazi plans to unleash apocalyptic destruction.

When a secret bunker and a vast network of tunnels are discovered after World War II, experts use cutting-edge tech to uncover if the high levels of radiation in the area could be connected to a classified Nazi nuclear program.

A strange, abandoned mansion on a remote island is central to countless conspiracy theories, and new discoveries reveal if this eerie site was a secret Nazi base intended for a sinister mission.

Germany's preparations for WW2 began years before 1939. Under various guises, Germany began work on what would become their most technologically advanced front.

When a top-secret Nazi base is discovered in France decades after the war ends, experts use cutting-edge tech to reveal the secrets of this compound; what they find could change everything we know about D-Day and the last stand of the Nazi regime.

Secrets of Hitler's Castle: When the Nazis took Ksiaz Castle, it wasn't for the view. Secret staircases and lifts were built, while underneath, a vast network of tunnels was taking form. S2 Ep6

New discoveries on the Channel Island of Guernsey, strangely fortified by the Nazis, reveal the terrifying truth behind Hitler's secret plan to win World War II at all costs, and using the latest science and tech, experts investigate what really happened here.

Built in 1934, Ordensburg Vogelsang, a virtual Nazi Castle was constructed with the intention of building the New German; elite future leaders of the Reich.