Historic house
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.
Houses were first thought of as historic rather than just old or interesting, during the early nineteenth century. Government protection was first given during the late nineteenth century.
Historic homes are often eligible for special grant awards for preservation. What makes a historic home significant is often its architecture or its significance to the culture or history of the area. There are some organizations that offer services to research the history of a home and others that provide repositories for users to document the history of their homes.
Historic homes may still be inhabited, and thus should not be confused with historic house museums.
en.wikipedia.org