The Książ Castle Underground and Project Riese
What the tunnels beneath the castle are, who dug them, and how to visit
The tunnels beneath Książ are one of the most talked-about sights in Lower Silesia. Here is what they are and how to see them.
What Project Riese was
'Riese' — German for 'giant' — was a massive construction project undertaken by Nazi Germany between 1943 and 1945, made up of several underground complexes in Lower Silesia, including one at Książ Castle and others in the nearby Owl Mountains. Its true purpose was never officially confirmed, and the work was left unfinished when the war ended. Thousands of forced labourers were used in its construction.
Visiting the Underground Route
The guided Underground Tourist Route takes small groups through the raw rock passages beneath the castle on a fixed timed slot. It is cool underground all year, so bring a warm layer, and expect uneven ground and steps. Because group sizes are limited, the summer slots are the one thing at Książ that reliably sells out — book ahead.
Frequently asked
Was the underground finished?
No. Like the rest of Project Riese, the tunnels under and around Książ were never completed. That unfinished, raw state is much of what makes them so striking to walk.
Do I need to book the underground in advance?
In summer, yes. The route runs on timed slots for small groups and the popular afternoon walks sell out days ahead. We reserve the slot you want at checkout.