This layer contains polygons representing individual properties, usually a single parcel or building. The GIS data layer was created from paper documents. The Historical_LandmarksEasements layer contains individual parcels and buildings that are designated by the City Council as Cambridge Landmarks or that are protected by way of a voluntary donation of a preservation easement (aka preservation restriction) by a property owner to the City’s Historical Commission. Changes to the layer come about a few times a year as new landmarks and easements are so designated.