U.S. Department of the Interior, National Park Service
VIII. HOW TO EVALUATE THE INTEGRITY OF A PROPERTY
Integrity is the ability of a property to convey its significance. To be listed in the National Register of Historic Places, a property must not only be shown to be significant under the National Register criteria, but it also must have integrity. The evaluation of integrity is sometimes a subjective judgment, but it must always be grounded in an understanding of a property's physical features and how they relate to its significance.
Historic properties either retain integrity (this is, convey their significance) or they do not. Within the concept of integrity, the National Register criteria recognizes seven aspects or qualities that, in various combinations, define integrity.
To retain historic integrity a property will always possess several, and usually most, of the aspects. The retention of specific aspects of integrity is paramount for a property to convey its significance. Determining which of these aspects are most important to a particular property requires knowing why, where, and when the property is significant. The following sections define the seven aspects and explain how they combine to produce integrity.
SEVEN ASPECTS OF INTEGRITY
Understanding the Aspects of Integrity
Location is the place where the historic property was constructed or the place where the historic event occurred. The relationship between the property and its location is often important to understanding why the property was created or why something happened. The actual location of a historic property, complemented by its setting, is particularly important in recapturing the sense of historic events and persons. Except in rare cases, the relationship between a property and its historic associations is destroyed if the property is moved. (See Criteria Consideration B in Part VII: How to Apply the Criteria Considerations, for the conditions under which a moved property can be eligible.)
Design is the combination of elements that create the form, plan, space, structure, and style of a property. It results from conscious decisions made during the original conception and planning of a property (or its significant alteration) and applies to activities as diverse as community planning, engineering, architecture, and landscape architecture. Design includes such elements as organization of space, proportion, scale, technology, ornamentation, and materials.
A property's design reflects historic functions and technologies as well as aesthetics. It includes such considerations as the structural system; massing; arrangement of spaces; pattern of fenestration; textures and colors of surface materials; type, amount, and style of ornamental detailing; and arrangement and type of plantings in a designed landscape.
Design can also apply to districts, whether they are important primarily for historic association, architectural value, information potential, or a combination thereof. For districts significant primarily for historic association or architectural value, design concerns more than just the individual buildings or structures located within the boundaries. It also applies to the way in which buildings, sites, or structures are related: for example, spatial relationships between major features; visual rhythms in a streetscape or landscape plantings; the layout and materials of walkways and roads; and the relationship of other features, such as statues, water fountains, and archeological sites.
Setting is the physical environment of a historic property. Whereas location refers to the specific place where a property was built or an event occurred, setting refers to the character of the place in which the property played its historical role. It involves how, not just where, the property is situated and its relationship to surrounding features and open space.
Setting often reflects the basic physical conditions under which a property was built and the functions it was intended to serve. In addition, the way in which a property is positioned in its environment can reflect the designer's concept of nature and aesthetic preferences.
The physical features that constitute the setting of a historic property can be either natural or manmade, including such elements as:
These features and their relationships should be examined not only within the exact boundaries of the property, but also between the property and its surroundings. This is particularly important for districts.
Materials are the physical elements that were combined or deposited during a particular period of time and in a particular pattern or configuration to form a historic property. The choice and combination of materials reveal the preferences of those who created the property and indicate the availability of particular types of materials and technologies. Indigenous materials are often the focus of regional building traditions and thereby help define an area's sense of time and place.
A property must retain the key exterior materials dating from the period of its historic significance. If the property has been rehabilitated, the historic materials and significant features must have been preserved. The property must also be an actual historic resource, not a recreation; a recent structure fabricated to look historic is not eligible. Likewise, a property whose historic features and materials have been lost and then reconstructed is usually not eligible. (See Criteria Consideration E in Part VII: How to Apply the Criteria Considerations for the conditions under which a reconstructed property can be eligible.)
Workmanship is the physical evidence of the crafts of a particular culture or people during any given period in history or prehistory. It is the evidence of artisans' labor and skill in constructing or altering a building, structure, object, or site. Workmanship can apply to the property as a whole or to its individual components. It can be expressed in vernacular methods of construction and plain finishes or in highly sophisticated configurations and ornamental detailing. It can be based on common traditions or innovative period techniques.
Workmanship is important because it can furnish evidence of the technology of a craft, illustrate the aesthetic principles of a historic or prehistoric period, and reveal individual, local, regional, or national applications of both technological practices and aesthetic principles. Examples of workmanship in historic buildings include tooling, carving, painting, graining, turning, and joinery. Examples of workmanship in prehistoric contexts include Paleo-Indian clovis projectile points; Archaic period beveled adzes; Hopewellian birdstone pipes; copper earspools and worked bone pendants; and Iroquoian effigy pipes.
Feeling is a property's expression of the aesthetic or historic sense of a particular period of time. It results from the presence of physical features that, taken together, convey the property's historic character. For example, a rural historic district retaining original design, materials, workmanship, and setting will relate the feeling of agricultural life in the 19th century. A grouping of prehistoric petroglyphs, unmarred by graffiti and intrusions and located on its original isolated bluff, can evoke a sense of tribal spiritual life.
Association is the direct link between an important historic event or person and a historic property. A property retains association if it is the place where the event or activity occurred and is sufficiently intact to convey that relationship to an observer. Like feeling, association requires the presence of physical features that convey a property's historic character. For example, a Revolutionary War battlefield whose natural and manmade elements have remained intact since the 18th century will retain its quality of association with the battle.
Because feeling and association depend on individual perceptions, their retention alone is never sufficient to support eligibility of a property for the National Register.
Integrity is based on significance: why, where, and when a property is important. Only after significance is fully established can you proceed to the issue of integrity.
The steps in assessing integrity are:
Ultimately, the question of integrity is answered by whether or not the property retains the identity for which it is significant.
DEFINING THE ESSENTIAL PHYSICAL FEATURES
All properties change over time. It is not necessary for a property to retain all its historic physical features or characteristics. The property must retain, however, the essential physical features that enable it to convey its historic identity. The essential physical features are those features that define both why a property is significant (Applicable Criteria and Areas of Significance) and when it was significant (Periods of Significance). They are the features without which a property can no longer be identified as, for instance, a late 19th century dairy barn or an early 20th century commercial district.
Criteria A and B
A property that is significant for its historic association is eligible if it retains the essential physical features that made up its character or appearance during the period of its association with the important event, historical pattern, or person(s). If the property is a site (such as a treaty site) where there are no material cultural remains, the setting must be intact.
Archeological sites eligible under Criteria A and B must be in overall good condition with excellent preservation of features, artifacts, and spatial relationships to the extent that these remains are able to convey important associations with events or persons.
A property important for illustrating a particular architectural style or construction technique must retain most of the physical features that constitute that style or technique. A property that has lost some historic materials or details can be eligible if it retains the majority of the features that illustrate its style in terms of the massing, spatial relationships, proportion, pattern of windows and doors, texture of materials, and ornamentation. The property is not eligible, however, if it retains some basic features conveying massing but has lost the majority of the features that once characterized its style.
Archeological sites eligible under Criterion C must be in overall good condition with excellent preservation of features, artifacts, and spatial relationships to the extent that these remains are able to illustrate a site type, time period, method of construction, or work of a master.
For properties eligible under Criterion D, including archeological sites and standing structures studied for their information potential, less attention is given to their overall condition, than it they were being considered under Criteria A, B, or C. Archeological sites, in particular, do not exist today exactly as they were formed. There are always cultural and natural processes that alter the deposited materials and their spatial relationships.
For properties eligible under Criterion D, integrity is based upon the property's potential to yield specific data that addresses important research questions, such as those identified in the historic context documentation in the Statewide Comprehensive Preservation Plan or in the research design for projects meeting the Secretary of the Interior's Standards for Archeological Documentation.
Some historic buildings are virtually defined by their exteriors, and their contribution to the built environment can be appreciated even if their interiors are not accessible. Examples of this would include early examples of steel-framed skyscraper construction. The great advance in American technology and engineering made by these buildings can be read from the outside. The change in American popular taste during the 19th century, from the symmetry and simplicity of architectural styles based on classical precedents, to the expressions of High Victorian styles, with their combination of textures, colors, and asymmetrical forms, is readily apparent from the exteriors of these buildings.
Other buildings "are" interiors. The Cleveland Arcade, that soaring 19th century glass-covered shopping area, can only be appreciated from the inside. Other buildings in this category would be the great covered train sheds of the 19th century.
In some cases the loss of an interior will disqualify properties from listing in the National Register--a historic concert hall noted for the beauty of its auditorium and its fine acoustic qualities would be the type of property that if it were to lose its interior, it would lose its value as a historic resource. In other cases, the overarching significance of a property's exterior can overcome the adverse effect of the loss of an interior.
In borderline cases particular attention is paid to the significance of the property and the remaining historic features.
For a district to retain integrity as a whole, the majority of the components that make up the district's historic character must possess integrity even if they are individually undistinguished. In addition, the relationships among the district's components must be substantially unchanged since the period of significance.
When evaluating the impact of intrusions upon the district's integrity, take into consideration the relative number, size, scale, design, and location of the components that do not contribute to the significance. A district is not eligible if it contains so many alterations or new intrusions that it no longer conveys the sense of a historic environment.
A component of a district cannot contribute to the significance if:
VISIBILITY OF PHYSICAL FEATURES
Properties eligible under Criteria A, B, and C must not only retain their essential physical features, but the features must be visible enough to convey their significance. This means that even if a property is physically intact, its integrity is questionable if its significant features are concealed under modern construction. Archeological properties are often the exception to this; by nature they usually do not require visible features to convey their significance.
If the historic exterior building material is covered by non-historic material (such as modern siding), the property can still be eligible if the significant form, features, and detailing are not obscured. If a property's exterior is covered by a non-historic false-front or curtain wall, the property will not qualify under Criteria A, B, or C, because it does not retain the visual quality necessary to convey historic or architectural significance. Such a property also cannot be considered a contributing element in a historic district, because it does not add to the district's sense of time and place. If the false front, curtain wall, or non-historic siding is removed and the original building materials are intact, then the property's integrity can be re-evaluated.
Property Contained within Another Property
Some properties contain an earlier structure that formed the nucleus for later construction. The exterior property, if not eligible in its own right, can qualify on the basis of the interior property only if the interior property can yield significant information about a specific construction technique or material, such as rammed earth or tabby. The interior property cannot be used as the basis for eligibility if it has been so altered that it no longer contains the features that could provide important information, or if the presence of important information cannot be demonstrated.
A sunken vessel can be eligible under Criterion C as embodying the distinctive characteristics of a method of construction if it is structurally intact. A deteriorated sunken vessel, no longer structurally intact, can be eligible under Criterion D if the remains of either the vessel or its contents is capable of yielding significant information. For further information, refer to National Register Bulletin: Nominating Historic Vessels and Shipwrecks to the National Register of Historic Places.
A natural feature that is associated with a historic event or trend, such as a rock formation that served as a trail marker during westward expansion, must retain its historic appearance, unobscured by modern construction or landfill. Otherwise it is not eligible, even though it remains intact.
COMPARING SIMILAR PROPERTIES
For some properties, comparison with similar properties should be considered during the evaluation of integrity. Such comparison may be important in deciding what physical features are essential to properties of that type. In instances where it has not been determined what physical features a property must possess in order for it to reflect the significance of a historic context, comparison with similar properties should be undertaken during the evaluation of integrity. This situation arises when scholarly work has not been done on a particular property type or when surviving examples of a property type are extremely rare. (See Comparing Related Properties in Part V: How to Evaluate a Property within its Historic Context.)
Rare Examples of a Property Type
Comparative information is particularly important to consider when evaluating the integrity of a property that is a rare surviving example of its type. The property must have the essential physical features that enable it to convey its historic character or information. The rarity and poor condition, however, of other extant examples of the type may justify accepting a greater degree of alteration or fewer features, provided that enough of the property survives for it to be a significant resource.
DETERMINING THE RELEVANT ASPECTS OF INTEGRITY
Each type of property depends on certain aspects of integrity, more than others, to express its historic significance. Determining which of the aspects is most important to a particular property requires an understanding of the property's significance and its essential physical features.
Criteria A and B
A property important for association with an event, historical pattern, or person(s) ideally might retain some features of all seven aspects of integrity: location, design, setting, materials, workmanship, feeling, and association. Integrity of design and workmanship, however, might not be as important to the significance, and would not be relevant if the property were a site. A basic integrity test for a property associated with an important event or person is whether a historical contemporary would recognize the property as it exists today.
For archeological sites that are eligible under Criteria A and B, the seven aspects of integrity can be applied in much the same way as they are to buildings, structures, or objects. It is important to note, however, that the site must have demonstrated its ability to convey its significance, as opposed to sites eligible under Criterion D where only the potential to yield information is required.
A mid-19th century waterpowered mill important for its association with an area's industrial development is eligible if:
A mid-19th century waterpowered mill important for its association with an area's industrial development is not eligible if:
A property significant under Criterion C must retain those physical features that characterize the type, period, or method of construction that the property represents. Retention of design, workmanship, and materials will usually be more important than location, setting, feeling, and association. Location and setting will be important, however, for those properties whose design is a reflection of their immediate environment (such as designed landscapes and bridges).
For archeological sites that are eligible under Criterion C, the seven aspects of integrity can be applied in much the same way as they are to buildings, structures, or objects. It is important to note, however, that the site must have demonstrated its ability to convey its significance, as opposed to sites eligible under Criterion D where only the potential to yield information is required.
A 19th century wooden covered bridge, important for illustrating a construction type, is eligible if:
For a 19th century wooden covered bridge, important for its construction type, replacement of some materials of the flooring, siding, and roofing would not necessarily damage its integrity. Integrity would be lost, however, if:
For properties eligible under Criterion D, setting and feeling may not have direct bearing on the property's ability to yield important information. Evaluation of integrity probably will focus primarily on the location, design, materials, and perhaps workmanship.
A multicomponent prehistoric site important for yielding data on changing subsistence patterns can be eligible if:
A multicomponent prehistoric site important for yielding data on changing subsistence patterns would not be eligible if:
A lithic scatter site important for yielding data on lithic technology during the Late Archaic period can be eligible if:
A lithic scatter site important for yielding data on lithic technology during the Late Archaic period would not be eligible if:
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