Gov. John Langdon Mansion
Built 1784. Added to the National Register in 1974, and a National Historic Landmark.
The record
| Register name | Langdon, Gov. John, Mansion |
| Property type | Building |
| Address | 143 Pleasant St., Portsmouth, NH |
| County | Rockingham County |
| Listed | Dec 2, 1974 |
| Listed for | Politics and government |
| Level of significance | National |
| Reference number | 74000197 |
| Built | 1784 · more from the 1780s |
| Style | Georgian architecture |
| Designations | National Historic Landmark |
The nomination form, the document that argues why this place matters, is in the National Archives: Read the nomination ↗
Visiting
| Address | 143 Pleasant St., Portsmouth, NH |
| Coordinates | 43.0753° N, 70.7564° W · Directions ↗ |
| Also in Portsmouth | 42 listed places in Portsmouth → · walking tours → |
Explore
Map
Nearby in Rockingham County
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Public land around it
| Great Bay National Wildlife Refuge ↗National Wildlife Refuge, U.S. Fish and Wildlife Service | About 4 miles away1,170 acres |
Wilderness Atlas publishes a centroid and an acreage for each unit, not a boundary line. Distance here is measured to a circle of the same area drawn around that centroid, so treat it as roughly right rather than surveyed.
Local history books for Portsmouth
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New Hampshire travel guides
Titles come from Open Library's catalog, matched by subject heading or by title.
Reference
Questions people ask
When was Gov. John Langdon Mansion listed on the National Register?
Dec 2, 1974. It is also a National Historic Landmark, the higher of the two designations.
Source: National Park Service
When was Gov. John Langdon Mansion built?
1784, in the Georgian architecture style.
Source: Wikidata
Where is Gov. John Langdon Mansion?
143 Pleasant St., Portsmouth, Rockingham County, New Hampshire.
Source: National Park Service
Where is the nomination form for Gov. John Langdon Mansion?
The National Archives holds the nomination form, the document that made the case for listing.
Source: National Archives
Is there a wildfire near Gov. John Langdon Mansion right now?
2 active incidents within 50 miles as of 2026-10-17, nearest Morse Rx, 38 miles away.
Source: Map
Sources
Name, location, type and dates come from the National Register office's spreadsheet of listed properties, because the Park Service's spatial data does not carry this listing. The map point comes from Wikidata. Construction date, architect, style, photograph and encyclopedia link come from Wikidata and Wikimedia Commons, matched on reference number 74000197. Nothing here is transcribed by hand. The nomination form and photographs ↗ at NPGallery are the original nomination as filed with the National Park Service, and the form is often the best description of the place.