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Historic Resource Types

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large brown gazebo with gold spires on top and red brick steps in a park surrounded by green grass and trees in the distance
Portland’s historic resources are unique artifacts of the city’s architectural, cultural, and historic past.
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Historic resource is a term broadly used to define a building, part of a building, structure, object, landscape, tree, site, place, or district as having or potentially having a significant relationship to events or conditions of the human past. Historic resources may be important for archaeological, architectural, cultural, or historical reasons. The City’s Historic Resource Inventory recognizes eight specific types of historic resource, each of which are described on this page.

The process of and criteria for documenting and evaluating the significance of historic resources has evolved since Portland’s first formal historic resource efforts in the 1960s, with decisions often reflecting the dominant societal values of the time. While high-style architecture and the residences of significant men have long been prioritized in historic preservation efforts, places significant to the histories, events, and conditions of historically marginalized communities have largely been excluded from past community-led and City-sponsored efforts. Because of this, many historic resources — including ones that convey social and cultural importance — have yet to be formally recognized in the City’s Historic Resource Inventory.

The eight types of historic resources are differentiated by their historic importance, the process by which they received recognition, and the different historic preservation land use regulations that apply to them. Some historic resources have been recognized with more than one type, e.g. a Historic Landmark located in a Conservation District. In these instances, the resource type subject to the most restrictive historic preservation land use regulations is generally the type shown in the Historic Resource Inventory. To learn about the regulations that apply to a specific historic resource, visit Making Changes to a Historic Resource.


Historic Landmark

4-story large white brick building on a main street corner
The 1912 Clyde Hotel is a Historic Landmark.

A Historic Landmark is a building, portion of a building, structure, object, landscape, tree, site, or place that has been formally designated for archaeological, architectural, cultural, or historical merit. Information describing a specific Historic Landmark’s physical attributes and historic significance can be found in the nomination prepared to justify its designation. Historic Landmarks are designated by the City, generally as the result of an owner-initiated land use review. The vast majority of Historic Landmarks are also federally listed in the National Register of Historic Places. Owner consent is required to designate a property as a Historic Landmark.

Demolition of Historic Landmarks requires approval through a land use review called Demolition Review. Alteration, addition, and new construction proposals affecting Historic Landmarks are subject to a form of design review called Historic Resource Review. The specific historic preservation land use regulations that apply to Historic Landmarks can be found in Portland Zoning Code Section 33.445.100.


Conservation Landmark

2-story house with gray stone on first level, angled roofline, and red cedar siding on second level
The 1909 Thomas and Alla Patterson House is a Conservation Landmark.

A Conservation Landmark is a building, portion of a building, structure, object, landscape, tree, site, or place that has been formally designated for archaeological, architectural, cultural, or historical merit. Information describing a specific Conservation Landmark’s physical attributes and historic significance can be found in the nomination prepared to justify its designation. Conservation Landmarks are designated by the City, generally as the result of an owner-initiated land use review. Owner consent is required to designate a property as a Conservation Landmark.

Demolition of Conservation Landmarks requires approval through a land use review called Demolition Review. Alterations, additions, and new construction affecting Conservation Landmarks is subject to a form of design review called Historic Resource Review. Unlike Historic Landmarks, alteration, addition, and new construction proposals affecting Conservation Landmarks can avoid Historic Resource Review if the proposal meets certain clear and objective design standards. The specific historic preservation land use regulations that apply to Conservation Landmarks can be found in Portland Zoning Code Section 33.445.110.


National Register Landmark

mixed-use building on a sharp street corner. Building is 2-stories with rounded corner, ground floor is glass front, second floor is brown brick with a horizontal row of small windows across the middle.
The 1922 Phoenix Pharmacy Building is a National Register Landmark.

A National Register Landmark is a building, structure, object, or site that has been listed in the federal National Register of Historic Places and has not been designated or identified by the City as a Historic or Conservation Landmark. Information describing a specific National Register Landmark’s physical attributes and historic significance are included in the nomination prepared to justify its listing. National Register Landmarks are listed by the National Park Service following a process administered by the Oregon State Historic Preservation Office. A National Register Landmark will not be listed if the property owner(s) oppose the listing.

Demolition of National Register Landmarks requires approval through a land use review called Demolition Review. The specific historic preservation land use regulations that apply to National Register Landmarks can be found in Portland Zoning Code Section 33.445.120.


Historic District

3-story red brick building on corner with large black pillars and curved glass windows on upper floor.
East Portland/Grand Avenue is a Historic District.

A Historic District is a geographic area designated for its special archaeological, architectural, cultural, or historical merit. Information describing a specific Historic District’s historic significance and physical attributes — including property-by-property descriptions — can be found in the nomination prepared to justify its designation. Historic Districts are designated by the City Council following a City-sponsored planning process. The affirmative consent of a majority of property owners is required to designate an area as a Historic District. All of Portland’s Historic Districts are also federally listed in the National Register of Historic Places.

Demolition of certain structures in Historic Districts requires approval through a land use review called Demolition Review. Alteration, addition, and new construction proposals within Historic Districts are subject to a form of design review called Historic Resource Review. The specific historic preservation land use regulations that apply in Historic Districts can be found in Portland Zoning Code Section 33.445.200.


Conservation District

brown single-story brick building with arched doorway at corner, picture windows on both sides, and picnic tables on sidewalk
Much of the Piedmont neighborhood is a Conservation District.

A Conservation District is a geographic area designated for its special archaeological, architectural, cultural, or historical merit. Information describing a specific Conservation District’s physical attributes and historic significance can be found in the documentation prepared to justify its designation. Conservation Districts are designated by the City Council, following a City-sponsored planning process. The affirmative consent of a majority of property owners is required to designate an area as a Conservation District.

Demolition of certain structures in Conservation Districts requires approval through a land use review called Demolition Review. Alteration, addition, and new construction proposals within Conservation Districts are subject to a form of design review called Historic Resource Review. Unlike Historic Districts, alteration, addition, and new construction proposals in Conservation Districts can avoid Historic Resource Review if the proposal meets certain clear and objective design standards. The specific historic preservation land use regulations that apply in Conservation Districts can be found in Portland Zoning Code Section 33.445.210.


National Register District

sidewalk with arched stone sculpture curving over, with tan ornate large single-family home in background
The Laurelhurst neighborhood is a National Register District.

A National Register District is a geographic area that has been listed in the National Register of Historic Places and has not been designated or identified by the City as a Historic District or Conservation District. Information describing a specific National Register District’s historic significance and physical attributes — including property-by-property descriptions — can be found in the nomination prepared to justify its listing. National Register Districts are listed by the National Park Service following a process administered by the Oregon State Historic Preservation Office. A National Register District will not be listed if a majority of affected property owners oppose the listing.

Demolition of certain structures in National Register Districts requires approval through a land use review called Demolition Review. The specific historic preservation land use regulations that apply in National Register Districts can be found in Portland Zoning Code Section 33.445.220.


Significant Resource

domed building of worship with circular concrete wall on ground floor and domed brick roof
The 1965 Congregation Ahavath Achim Synagogue is a Significant Resource.

A Significant Resource is a is a building, portion of a building, structure, object, landscape, tree, site, or place that the City has determined to be significant for its archaeological, architectural, cultural, or historical merit. Rank I, II, III resources identified in the 1984 Historic Resource Inventory are Significant Resources. Significant Resources are listed by the City Council following a City-sponsored planning process. Owner consent is not required for a historic resource to be determined a Significant Resource.

Demolition of Significant Resources requires 120-Day Demolition Delay. The specific historic preservation land use regulations that apply to Significant Resources can be found in Portland Zoning Code 33.445 Sections 320 through 340.


Documented Resource

Single-level building with flat roof, freestanding brick wall and gray exterior
The 1952 Wolfman Building is a Documented Resource.

A Documented Resource is a historic resource that has been documented by the City but has not been formally designated as a Landmark or District or determined to be a Significant Resource. Unranked resources identified in the 1984 Historic Resource Inventory are Documented Resources.

Unlike the other historic resource types included in the City’s Historic Resources Inventory, Documented Resources are not subject to historic preservation land use regulations.