The Abandoned House in Cheydinhal is located along the west wall near the Great Chapel of Arkay. Upstairs is crushed furniture and some miscellaneous items. The basement houses the door to the Dark Brotherhood Sanctuary, though the Hero won't be able to open it until Lucien Lachance tells them the password after completing the quest "A Knife in the Dark." The Count of Cheydinhal refuses to even acknowledge its existence.