Shadowmarks

Eagle-eyed adventurers may notice that some locations across Skyrim are marked with strange glyphs. Unbeknownst to most, these runes are actually symbols used by the Thieves Guild to indicate locations that members feel are particularly wealthy targets, safe, dangerous, or have inhabitants that may be helpful or problematic. These symbols are known as Shadowmarks. To learn more about Shadowmarks, search the Thieves Guild for a book written by Delvin Mallory called Shadowmarks, which lists all of the markings that the Thieves Guild uses.