Inside the Polish fairytale castle with a dark Nazi past, a labyrinth of secret tunnels and a long-lost 'golden train' filled with hidden treasures

Published: 07:29 EDT, 28 October 2026 | Updated: 07:32 EDT, 28 October 2026 On the surface, it looks like a fairytale castle, painted in shades of pink and orange that wouldn't go amiss in a Disney film.But Książ Castle in Poland hides a dark secret beneath its glossy surface, with links to the Nazi party and Second World War history.Perched atop a hill in Walbrzych, in southwestern Poland, it is the country's third-largest castle, and dates back to the Middle Ages.However, this gargantuan property was seized by the Nazis in 1941, earmarked as a potential residence for Hitler – and a bunker was built 50 metres beneath the castle to protect from bombing.Deep within the Owl Mountains, the site made headlines in 2015 when treasure-hunters located alleged gold near the site.Tunnels and bunkers were built using forced labour, but much of the subterranean complex remains embroiled in mystery. Książ Castle in Poland is a prominent tourist attraction due to its historical rootsCode-named 'Riese' ('Giant'), the project of forming these tunnels was kept top-secret. While the project was never fully completed, tales of the treasure hidden in the area are aplenty. For one, rumours have suggested a gold train is hidden somewhere within the labyrinth. Allegedly, when Nazis retreated from Wrocław – then Breslau – in 1945, they hid a train filled with valuables in the Owl Mountains, CNN reported. In 2015, two men – Piotr Koper from Poland and German Andreas Richter – claimed to have found an armoured railway carriage there from the war that was allegedly filled with treasures. It added to the global buzz around a possible Second World War 'gold train' in the area. An underground tunnel complex beneath the castle is accessible to the public on guided tours Inside, the castle remains well maintained with an air of opulenceHowever, the truth of these claims was not confirmed, meaning it remains well within the realm of legend. Nonetheless, the destroyed or hidden entrances to many of the still-undiscovered tunnels keep the rumours alive.The official castle website adds: 'According to the notes of Adolf Hitler's favourite architect, Albert Speer, as well as other available documents, it is possible that the tunnels were even twice as extensive as those which are already known about – that is, 3,200 square metres.'Inside, the castle is decorated with elaborate chandeliers, fireplaces and stunning painted ceilings.Large windows, mirrors and decor that would fit in with royal palaces across Europe are everywhere you look. You can book tours of the castle online, with all-day fees covering the castle and underground from 92 PLN (£17.50). Ceilings are impressive, and the beautiful interiors are a far cry from the darker roots below the castleFor history buffs, Poland is a treasure trove of Second World War sites to visit – not least Wolin Underground City, previously known as Vineta Battery, a bunker built between 1935 and 1939.Made up of seven bunkers, the fortress was used by the Nazis to guard the coastline.Nowadays, the entire site is a museum that is open to the public and is constantly being expanded and restored.Wolin Island, which houses the underground site, is located in Poland's West Pomeranian region, which belonged to Germany before the Second World War – and was used by Hitler to ramp up defence.