American Philosophical Society Hall
Also known as: See Also:Independence National Historical Park
Why it's listed
Built in Late Georgian style on a lot awarded by the Pennsylvania Assembly in 1785, this two-and-a-half story brick hall on South Fifth Street in Independence Square was completed in 1789 and held its first meeting that year. Its hip roof had two gabled dormers on the east and west faces, and its central doorways carried a round arch over a basket-weave fanlight. The building housed the American Philosophical Society, founded by Benjamin Franklin's circle and merged with a rival group in 1768. Its significance rests on the society's early scientific work, including observations of the 1769 transit of Venus and the first volume of its Transactions in 1771. The hall also served as a museum and a place where inventions such as John Fitch's steamboat were exhibited. Its library holds the Lewis and Clark Expedition records, the Mason and Dixon records and a large Franklin collection. A third story added in 1890 was removed in 1946 to restore the original appearance.
Significance in brief: The nomination argues the building is significant as the home of one of America's oldest learned and scientific societies, whose origins trace to Benjamin Franklin's 1743 call for a society and whose 1768 merger formed the organization that exists today. It also cites the society's early scientific work, including observations of the 1769 transit of Venus and the publication of its Transactions from 1771, and its library and collections.
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 66000675, listed October 15, 1966. Summary generated October 2026 (model claude-haiku-5-5, prompt v1.1-2026-10-29, confidence medium).
Key facts
| Address | Independence Sq., Philadelphia |
|---|---|
| County | Philadelphia |
| Listed | October 15, 1966 |
| Reference number | 66000675 |
| Resource type | Building |
| Period of significance | 1768-1789 |
| Architectural style | Late Georgian |
| Criteria |
|
| Areas of significance | Science, Religion, Social History, Invention |
| Level of significance | National |
| National Historic Landmark | Yes, designated January 12, 1965 |
| Status (as stated in the nomination) | The third story added in 1890 was removed in 1946 to restore the historic appearance; the library is now housed across Fifth Street. |
| Acreage | 0.9 |
| Coordinates | 39.94863, -75.14946 (NPS GIS) |
What listing means for this property
National Register listing is honorary for a privately owned home: it does not by itself restrict what an owner may do with their own money, and it does not require public access. Restrictions come from local landmark or historic-district ordinances, which are separate (how they differ).
Owner-occupied houses are not eligible for the 20% federal rehabilitation tax credit, which applies to income-producing buildings, but many states offer credits for homeowners. Listing also opens the door to preservation easements and to buying a plaque. Start with what listing means for homeowners, renovating a listed house and selling one.
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 66000675.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q7186170
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.