I can personally attest that Wewelsburg castle is but an extremely powerful portal (channel, conduit) of supernatural energy.
Some occultists believe that this immensely powerful energy is the mythical (or not-so-mythical) Mjölnir – the Hammer of Thor. According to Norse mythology, it is one of the most powerful supernatural (magical) spiritual weapons in the Universe – if not the most powerful. Some also believe that the mysterious Vril energy and Mjölnir are one and the same thing.
Consequently, the somewhat artificial (synthetic) neo-pagan deity Irmin worshipped by Willigut is no other than the Norse god Thor. And the Wewelsburg castle is simply modern temple of Thor.