A historic house generally meets several criteria before being listed by an official body as "historic." Generally the building is at least a certain age, depending on the rules for the individual list. A second factor is that the building be in recognizably the same form as when it became historic. Third is a requirement that either an event of historical importance happened at the site, or that a person of historical significance was associated with the site, or that the building itself is important for its architecture or interior.