Claudius Arcadia's House is located in the Talos Plaza District of the Imperial City. There is a note posted on the door to this house by the Imperial Legion, detailing the attempted prayer to the Night Mother and contacting of the Dark Brotherhood by the owner of the house, Claudius Arcadia.
The Dark BrotherhoodEdit
Upon completion of the Hero's initiation into the Dark Brotherhood through the killing of Rufio, Arcadia can be found in a cell in the Imperial Prison and will complain to them about the unjust nature of his situation.
Through dialogue with Rufio, immediately prior to his death, it is revealed that Arcadia sought Rufio's death for some invasive action Rufio took against a woman who Arcadia presumably knows, or knew.