A preserved site is a structure open to visitors who come to view the structure for its own sake, or to view it as it would have been used when it served its original purpose. This includes house-museums, architectural sites open permanently to visitors, and historic sites whose main usage is to be seen by the public.

The structure itself is the object of the visit. Rooms or settings can show how it was used in its original role.

Historic status alone is insufficient. The public-viewing purpose distinguishes this usage from an old building that continues mainly as a home, workplace, or other active use.