{"nrhp_refnum":"10001030","name":"Greenbelt Knoll Historic District","other_names":[],"category":"district","location":{"address":"I-19 Longford St, roughly bounded by Holme Ave and Pennypack Park Greenway","address_restricted":false,"city":"Philadelphia","county":"Philadelphia","state":"PA","lat":40.05720343300004,"lon":-75.02131740499993,"geom_source":"nps_gis"},"listed_date":"2010-12-14","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Social History","Architecture"],"significance_levels":["local"],"summary":{"what_it_is":"Greenbelt Knoll is a nine-acre residential historic district of 18 modest one-story Modern frame houses on a cul-de-sac called Longford Street in suburban northeastern Philadelphia, constructed in 1955 and 1956. It includes detached garages, an artist's studio, and a 2-acre communal park along the Pennypack Park Greenway.","why_significant":"The nomination argues the district is significant for its association with the development of integrated housing in post-World War II Philadelphia and with developer Morris Milgram, who lived there until 1976. It is also regarded as locally significant for its Modern architecture, designed by Montgomery & Bishop with Harry Duncan, Margaret Lancaster Duncan and consultant Louis I. Kahn, and as one of the most important concentrations of residential Modernist buildings in the city.","narrative":"Greenbelt Knoll is a small residential district of 18 one-story frame houses on a wooded knoll in northeastern Philadelphia, built in 1955 and 1956 on lots of roughly one-third acre along a cul-de-sac called Longford Street. The houses share a low-pitched roof, broad eaves, vertical wood siding and projecting triangular brick fireplaces, yet none is an exact copy of another, since each was shaped by its site. The design kept most trees, and some grow through deck floors and breezeways. Morris Milgram developed the project as one of his integrated housing communities and lived there from its construction until 1976. Its significance rests on its role in the struggle for fair housing in the post-war North, and on its Modern architecture, which the nomination regards as among the most important groupings of residential Modernist buildings in Philadelphia.","period_of_significance":"1956-1960","architect_builder":"Montgomery & Bishop (architects); Harry Duncan (architect); Margaret Lancaster Duncan (landscape architect); Louis I. Kahn (consultant)","architectural_style":"Modern","criteria":["A","B","C"],"status_note":"Seventeen houses are contributing; the house at 12 Longford was rebuilt after a fire and is non-contributing, and the house on lot #17 was demolished in 1997 and is now open space.","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:10:27.235053-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/10001030.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/10001030/41f63fe7e2-800.webp","url_1600":"https://nationalhistoricalregister.com/media/10001030/41f63fe7e2-1600.webp","licence":"Public domain","author":"Smallbones","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Greenbelt_Knoll.JPG\" rel=\"noopener\">Smallbones</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Greenbelt_Knoll.JPG"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71997550","wikipedia":"https://en.wikipedia.org/wiki/Greenbelt_Knoll","wikidata":"https://www.wikidata.org/wiki/Q15222112"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/philadelphia/greenbelt-knoll-historic-district-10001030/"}