Meaning of the Number Twelve
The chamber containing the Black Sun is known as the Obergruppenfuhrersaal, the Generals' Hall. Besides the Black Sun having twelve arms, this chamber also has twelve columns and twelve niches along the wall. There were twelve branches of the SS, so that may have been the relevance.
Other have advanced a comparison to the twelve knights of the round table. Himmler was a great fan of mythology and folklore, and two of the reading rooms within the castle were named Konig Artus (King Arthur) and Gral (Grail). As head of the SS, Himmler could potentially have also used such imagery in organizing the SS into twelve branches.
The number twelve also has relevance within Norse mythology. There are twelve Aesir gods, for example. Important groups of twelve can be found in other cultures as well, such as the twelve Olympic gods in Greek mythology and the twelve disciples who followed Jesus.
Beneath the Obergruppenfuhrersaal is another chamber that became known as the crypt or vault. It holds twelve seats against a wall surrounding a depression in the floor. The depression was meant to hold an eternal flame, a light emerging from darkness and rising up toward a swastika in the ceiling and then the Black Sun on the floor above.
