{"nrhp_refnum":"67000005","name":"Room 405, George Herbert Jones Laboratory, The University of Chicago","other_names":[],"category":"building","location":{"address":"S. Ellis Ave. between E. 57th and 58th Sts.","address_restricted":false,"city":"Chicago","county":"Cook County","state":"IL","lat":41.79037692400004,"lon":-87.60107409499994,"geom_source":"nps_gis"},"listed_date":"1967-05-28","is_nhl":true,"nhl_designated_date":"1967-05-28","areas_of_significance":["Science"],"significance_levels":["national"],"summary":{"what_it_is":"Room 405 is a small laboratory room, about six by nine feet, on the fourth floor of the George Herbert Jones Chemical Laboratory (built 1929) on the University of Chicago campus in Chicago, Cook County, Illinois.","why_significant":"In this room in 1942, chemists led by Glenn T. Seaborg first isolated a pure compound of the man-made element plutonium. Weeks later, B. B. Cunningham and L. B. Werner prepared the first weighable sample of a synthetic element. The form calls this a milestone in the development of nuclear energy.","narrative":"Room 405 is a small, pantry-like laboratory room of roughly six by nine feet, with shelves and counters along each wall. It sits on the fourth floor of the George Herbert Jones Chemical Laboratory, a 1929 building on the northwest side of the University of Chicago's main quadrangle. In this room, a group of chemists directed by Glenn T. Seaborg first isolated a pure compound of plutonium on August 18, 1942. On September 10, 1942, B. B. Cunningham and L. B. Werner prepared the first weighable sample of a synthetic element. The nomination describes this first isolation and weighing as a milestone in the development of nuclear energy, since plutonium became a basic fuel for nuclear power reactors. The room is set up with laboratory equipment and can be viewed through a glass door. It looks almost the same as in photographs from about 1942. A 1973 explosion destroyed the building's basement and first floor but left the room undamaged.","period_of_significance":"1942","architect_builder":null,"architectural_style":null,"criteria":[],"status_note":"Room 405 is set up with laboratory equipment, can be viewed through a glass door, and looks virtually the same as in ca. 1942 photographs. It was undamaged by a 1973 explosion that destroyed the building's basement and first floor. The form checks occupied status and museum use.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:55:34.536509-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/84/8915/28891584/content/electronic-records/rg-079/NPS_IL/67000005_NHL.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/67000005/de88320bfd-800.webp","url_1600":"https://nationalhistoricalregister.com/media/67000005/de88320bfd-1600.webp","licence":"CC BY-SA 4.0","author":"Photograph by Mike Peel (www.mikepeel.net).","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:At_Chicago_2024_152.jpg\" rel=\"noopener\">Photograph by Mike Peel (www.mikepeel.net).</a>, <a href=\"https://creativecommons.org/licenses/by-sa/4.0\" rel=\"license noopener\">CC BY-SA 4.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:At_Chicago_2024_152.jpg"},"district":{"nrhp_refnum":"12000040","name":"Chicago Park Boulevard System Historic District","url":"https://nationalhistoricalregister.com/districts/illinois/chicago-park-boulevard-system-historic-district-12000040/"},"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/28891584","wikipedia":"https://en.wikipedia.org/wiki/George_Herbert_Jones_Laboratory","wikidata":"https://www.wikidata.org/wiki/Q5540529"},"indexable":true,"url":"https://nationalhistoricalregister.com/illinois/cook-county/room-405-george-herbert-jones-laboratory-the-university-of-chicago-67000005/"}