Magic Mapping was a level 4 Divinations/Earth Magic spell which revealed a portion of the map of your current floor. This spell revealed some dungeon features, but not secret doors or certain hidden chambers.
Although this spell can no longer be cast, reading a scroll of magic mapping has a similar, more powerful effect.
It was formerly found in the following sources:
Magic Mapping was removed in 0.6 with the removal of the Divinations school of magic.