Castle Naerytar

It has been partially restored and is now the home of the Stargazer Academy, a sisterhood of wizards and magicians devoted to virginity and astrology.

The stargazers have sought out this remote locale just because it is so hostile; the source holding is here, they want to practice their teachings and magic in seclusion, and consider the dangers to be tests of their mettle. Nobody has ever disappeared inside the walls of the castle, though some sisters have disappeared in the vicinity or on trip to and from the academy.

Source: Dungeon #71.