National Register of Historic Places property types

The U.S. National Register of Historic Places (NRHP) classifies its listings by various types of properties. Listed properties generally fall into one of five categories, though there are special considerations for other types of properties which do not fit into these five broad categories or fit into more specialized subcategories. The five general categories for NRHP properties are: building, district, object, site, and structure.

Listed properties (NRHP-listed properties) generally fall into one of five categories, though there are special considerations for other types of properties which do not fit into these five broad categories or fit into more specialized subcategories. The five general categories for NRHP properties are: building, structure, object, site, and district. When multiple like properties are submitted as a group and listed together, they are known as a Multiple Property Submission.

Buildings, as defined by the National Register, are structures intended to shelter some sort of human activity. Examples include a house, barn, hotel, church or similar construction. The term building, as in outbuilding, can be used to refer to historically and functionally related units, such as a courthouse and a jail, or a barn and a house.

Buildings included on the National Register of Historic Places (NRHP-listed buildings) must have all of their basic structural elements as parts of buildings, such as ells and wings; interiors or facades are not independently eligible for the National Register. As such, the whole building is considered during the nomination and its significant features must be identified. If a nominated building has lost any of its basic structural elements, it is considered a ruin and categorized as a site.

The National Register of Historic Places defines a historic district per U.S. federal law, last revised in 2004. According to the Register definition, a historic district is: "a geographically definable area, urban or rural, possessing a significant concentration, linkage, or continuity of sites, buildings, structures, or objects united by past events or aesthetically by plan or physical development. In addition, historic districts consist of contributing and non-contributing properties. Historic districts possess a concentration, linkage or continuity of the other four types of properties. Objects, structures, buildings and sites within a historic district are usually thematically linked by architectural style or designer, date of development, distinctive urban plan, and/or historic associations." For example, the largest collection of houses from 17th and 18th century America are found in the McIntire Historic District in Salem, Massachusetts.

Some NRHP-listed historic districts are further designated as National Historic Landmarks, and termed National Historic Landmark Districts. All National Historic Landmarks are NRHP-listed.

A contributing property is any building, structure, object or site within the boundaries of the district which reflects the significance of the district as a whole, either because of historic associations, historic architectural qualities or archaeological features. Another key aspect of the contributing property is historic integrity. Significant alterations to a property can damage its physical connections with the past, lowering its historic integrity.

Objects are usually artistic in nature, or small in scale when compared to structures and buildings. Though objects may be movable, they are generally associated with a specific setting or environment. Examples of NRHP-listed objects include monuments, sculptures and fountains.