Secrets of the Castle Książ have still not been discovered. Damages from the night of 17 to 18 August 1943 made by the Allied air forces to German rocket research center at Peenemunde on the island of Usedom, forced the Reich to relocate their Experimental Center to such a place that it is not only a top-secret, but also resistant to bombing raids. There are signs that Castle Ksiaz became that place.

Already in 1942 the Ksiaz brought workers from Italy, followed by 400 miners of Donbass. In 1944, the number of forced laborers and prisoners in the Książ was about 3000. Scientific and popular science literature refers to the huge quantities of building materials - reinforced concrete, steel, cement, sand, transported by wagons to Walbrzych of the Reich. These are the amounts that would not fit in their volume of the underground of Ksiaz so far discovered. On top of everything it is worth noting that the construction of the Książ held under the supervision of the Luftwaffe. None of the Hitler's lodging was not under leadership of Luftwaffe. Intensive works in the underground of the castle Ksiaz lasted continuously until the end, ie until 10 May, despite the fact that Hitler had already committed suicide, Festung Breslau capitulated, and the command of the German capitulation was signed the day before.

It was only the entry of Soviet troops into Wałbrzych May 10, 1945 in Książ interrupted work.

But what did all of these German workers in the basement of the castle in a situation where the Eastern Front moved to Berlin, and the Western Allies reached the Elba River?

In 1944, Germany has already started hiding in underground of cultural goods in facilities, mines and tunnels. Boguslaw Wołoszański, widely known TV presenter said that according to documents from the Archives in Koblenz, Książ from the summer of 1943 was to become a repository of documents SS and the Reich Security Main Office. The action was called codename Brabant Joseph I. It is claimed that at the end of the war to Ksiaz began arriving transports of large boxes filled with unknown objects. In the underground of Ksiaz we still can find many traces indicating clearly the deliberate blocking of strings tunnel. John Weiss, a former prisoner of the KL branch in Książ Gross Rosen, who managed to avoid death and take refuge in America, visited the undergrounds of castle in 1985. He assumed that nothing is like it was in the past and tunnels lack in many rooms. As it turns out the German war signature "streng geheim" despite the passage of years has not lost its power in the basement of the castle "Ksiaz".