Sanctuary is a manse discovered early in the game. It was a home for Sagacious Maiden of Rose in one of her former incarnations. It's properties are most likely as follows:
Sanctuary has a large first age library, which is apparantly undetectable to sidereal astrology. It also has a large underground hanger, which is empty. A room off of the hanger contains a training automaton. In a hidden room, there is a table which shows all demesnes in creation. Hearthstones are generated, with any aspect, by putting a bit of the desired element or celestial material in a basin in one of three rooms. Each room will genereate up to three levels of hearthstones, either as three level 1, a level 2 and a level 1, or a single level 3.