Pupin Physics Laboratories, Columbia University
Why it's listed
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.
Significance in brief: 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.
Machine-generated summary. This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail. Source: nomination document (PDF) · National Archives catalog entry. NRHP reference 66000550, listed October 15, 1966. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | Broadway and 120th St., New York |
|---|---|
| County | Manhattan |
| Listed | October 15, 1966 |
| Reference number | 66000550 |
| Resource type | Building |
| Period of significance | 1939 |
| Areas of significance | Science, Invention |
| Level of significance | National |
| National Historic Landmark | Yes, designated December 21, 1965 |
| Status (as stated in the nomination) | 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. |
| Acreage | 0.9 |
| Coordinates | 40.80999, -73.96134 (NPS GIS) |
What listing means for this property
For a publicly owned building or structure, listing mainly matters when federal funds, permits or licences are involved: projects then go through Section 106 review so effects on the property are considered. Listing also strengthens applications for preservation grants and, for leased income-producing uses, can enable the federal rehabilitation tax credit.
General information, not legal or tax advice. Rules change; confirm with your State Historic Preservation Office or a qualified adviser.
Sources and further reading
- National Park Service, National Register of Historic Places database (snapshot May 2026), reference 66000550.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q7260678
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.