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Photograph of Fort Jefferson
Photograph by U.S. National Park Service, Public domain. Via Wikimedia Commons.

Fort Jefferson National Monument

Built in 1847. Listed on the National Register of Historic Places in 1970. 3 historic topographic surveys show this location, the earliest from 1971.

From the record

“Fort Jefferson is a former U.S. military coastal fortress in the Dry Tortugas National Park of Florida. It is the largest brick masonry structure in the Americas, covering 16 acres (6.5 ha) and constructed of over 16 million bricks.”

Wikipedia article Fort Jefferson, CC BY-SA 4.0.

One of 50 National Register listings published here for Monroe County · listed in 1970 · category: District · built in 1847.

Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service

The listing

  • Address. 68 mi. W of Key West, in Gulf of Mexico, Dry Tortugas Islands, 33040
  • When was it listed? November 1970
  • Category. district
  • Census division. Key West
  • When was it built? 1847
  • National Register reference number. 70000069 - the number the National Park Service assigned this property when it was listed, and the key its nomination file is catalogued under at the National Archives.

Then and now

1971 to 1989

The ground this property stands on, surveyed 18 years apart. Drag the handle to wipe between them. Both sheets are United States Geological Survey originals; neither has been altered.

Topographic sheet covering Fort Jefferson National Monument, surveyed 1989
Topographic sheet covering Fort Jefferson National Monument, surveyed 1971

Maps showing this location

3 surveys

United States Geological Survey topographic sheets whose coverage includes this point. Matched by taking the middle of the area the National Park Service maps for this listing, then testing that coordinate against the published boundary of every sheet.

Listed places nearby

1 within 8 miles

Other National Register properties close enough to walk or drive between, ordered by distance from this one. Both positions come from the same geocoding pass that matched these properties to their map sheets.

Photograph PropertyDistance Listed
Dry Tortugas National Park0.1 miles1992

Sources for this property

National Archives recordThe nomination case file for reference 70000069 in Record Group 79.
Wikipedia articleCommunity-written account of this property, licensed CC BY-SA.
Monroe CountyAll 50 listed properties in this county.

Provenance

  • Listing record. National Park Service National Register of Historic Places, listed-properties dataset, current to 2026-05-22.
  • Map join. Address geocoded through the United States Census geocoder, then tested against the published boundary of every sheet in the USGS Historical Topographic Map Collection.
  • How this page is made. Listing fields come from federal records; map-sheet coverage is a labelled coordinate-to-boundary calculation, not a source-field claim.