Castle Williams
Also known as: The Tower
Why it's listed
Castle Williams is a round, three-story fort of red Newark sandstone on the northwest point of Governors Island, in New York Harbor. Begun in 1807 and finished in 1811, it was designed and built by Lieutenant Colonel Jonathan Williams, then Chief Engineer of the U.S. Army. The walls form three-fifths of a circle about two hundred feet across, forty feet high and eight feet thick at the base, with arched casemates supporting three tiers of guns. Two straight walls close the enclosure on the landward side, topped by a bartizan. Originally called "The Tower" and nicknamed "The Cheesebox," it carried more than one hundred cannon and, with Castle Clinton in the Battery, guarded the waterway to New York City. It was cited as a reason the British fleet did not attack the city during the War of 1812. Repairs came in 1833, 1836 and 1912, when interior buildings were removed, the fort became a military prison, and concrete galleries were added.
Significance in brief: The nomination presents it as an unusual military fortification and a notable example of a massive masonry bastion that still serves a useful function. Completed in 1811 with more than one hundred cannon, it was one of the reasons the British fleet did not attempt an assault on New York during the War of 1812. With its twin, Castle Clinton, it guarded the waterway between Governors Island and New York City.
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 72000864, listed July 31, 1972. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | Governors Island, New York |
|---|---|
| County | Manhattan |
| Listed | July 31, 1972 |
| Reference number | 72000864 |
| Resource type | Building |
| Period of significance | 19th Century (begun 1807; completed 1811) |
| Architect / builder | Lieutenant Colonel Jonathan Williams |
| Areas of significance | Military, Architecture |
| Level of significance | National |
| Status (as stated in the nomination) | Listed in good condition, altered, on its original site, and occupied. Converted into a military prison in 1912, with concrete galleries added inside the walls. Owned by the U.S. Coast Guard. |
| Acreage | 0.9 |
| Within district | Governors Island |
| Coordinates | 40.69284, -74.01939 (NPS GIS) |
What listing means for this property
National Register listing is honorary: it recognises significance and does not restrict what a private owner may do without federal money or permits. It unlocks the 20% federal rehabilitation tax credit for income-producing buildings, state credits in many states, and Section 106 review when federal agencies are involved. See what listing means in practice.
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 72000864.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q1049532
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.