{"nrhp_refnum":"66000550","name":"Pupin Physics Laboratories, Columbia University","other_names":[],"category":"building","location":{"address":"Broadway and 120th St.","address_restricted":false,"city":"New York","county":"Manhattan","state":"NY","lat":40.80999277600006,"lon":-73.96133654623665,"geom_source":"nps_gis"},"listed_date":"1966-10-15","is_nhl":true,"nhl_designated_date":"1965-12-21","areas_of_significance":["Science","Invention"],"significance_levels":["national"],"summary":{"what_it_is":"A 10-story brick physics building at Broadway and West 120th Street on the Columbia University campus in Manhattan, New York. Its basement housed the cyclotron used in a landmark 1939 experiment.","why_significant":"The nomination argues that the building's basement cyclotron was used on January 25, 1939 to split the uranium atom for the first time in the New World, just ten days after the first atom-splitting in Copenhagen. The success led to federal support for atomic research at Columbia and to the Manhattan District Project. The nomination ties this significance to science and invention.","narrative":"Pupin Physics Laboratories is a 10-story brick building with stone trim at the corners and cornice, standing at Broadway and West 120th Street on the Columbia University campus. Its windows are single-sash, one-over-one, with stone flathoods. The basement once held a cyclotron, its control room and tall water tanks that shielded against radiation. On January 25, 1939, Dr. John R. Dunning and colleagues used that cyclotron to split the uranium atom, the first time this was done in the New World. It came only ten days after the same feat in Copenhagen. Dunning wrote in his notebook, \"Here is real atomic energy.\" The result led to federal support for atomic research at Columbia and to the Manhattan District Project. The cyclotron was sent to the Smithsonian in 1964, but its large magnet remains in the basement. The building still serves as Columbia's physics building, with faculty, undergraduates and graduate students, and it is closed to the public.","period_of_significance":"1939","architect_builder":null,"architectural_style":null,"criteria":[],"status_note":"Still the working physics building of Columbia University. The cyclotron was dismantled in 1964 and sent to the Smithsonian Institution, but its large magnet remains in the basement. The building is not open to the public.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:50:39.104734-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_NY/66000550_NHL.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/66000550/e24a6c83a6-800.webp","url_1600":"https://nationalhistoricalregister.com/media/66000550/e24a6c83a6-1600.webp","licence":"Public domain","author":"Mikhail Klassen at English Wikipedia","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Pupin_Hall.jpg\" rel=\"noopener\">Mikhail Klassen at English Wikipedia</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Pupin_Hall.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/75315938","wikipedia":"https://en.wikipedia.org/wiki/Pupin_Hall","wikidata":"https://www.wikidata.org/wiki/Q7260678"},"indexable":true,"url":"https://nationalhistoricalregister.com/new-york/manhattan/pupin-physics-laboratories-columbia-university-66000550/"}