From an article on the real-life Indiana Jones:
One day in 1933 he received a mysterious telegram offering him 1,000 reichsmarks a month to write the sequel to Crusade Against the Grail. The telegram was unsigned, but he was instructed to go to an address in Berlin – 7 Prinz Albrechtstrasse.
When he arrived, he was understandably surprised to be greeted by the grinning figure of Heinrich Himmler, the head of Hitler’s SS. Not only had Himmler read Crusade Against the Grail; he’d virtually committed the thing to memory. For the first time in his life Rahn met someone even more obsessed with finding the Grail than he was. Indeed, so confident was Himmler of finding the Grail that he’d already prepared a castle – Wewelsburg in Westphalia – for its arrival. In the basement, surrounded by busts of prominent Nazis, was an empty plinth where the Grail would go.