Simon's House is a location seen in "Fionna Campbell". It is located in and it is assumed that after "Come Along With Me" or "Obsidian", Simon moved there where he works as a 21st century antiquarian. After in "Cheers", Simon states that he wants to move to be away from people who always violate his privacy by seeing him as an attraction.
Choose Goose also lived there after his corruption, as he was used as a spell battery by Simon.