(07-22-2018, 06:58 PM)nemonowan Wrote: We saw that Grindewald was in a prison in Germany (reasonable, because that is where he waged war, not in Britain), but got no details about how that prison works.
The (relevant) film of Deathly Hallows didn't (IIRC) go into this level of detail, but the book establishes that Nurmengard, where he was imprisoned alone, had formerly been his headquarters. (That's why my wizard-rock band, if I ever attempt one, will be called Nurmengard Ballet.)