This file is from Wikimedia Commons and may be used by other projects.
The description on its file description page there is shown below.
Summary
DescriptionBlockhouse at fort myers.jpg
English: This blockhouse was part of the U.S. Army Fort Myers, in Florida, in use during the Third Seminole War, and again during the American Civil War.
Public domain works must be out of copyright in both the United States and in the source country of the work in order to be hosted on the Commons. If the work is not a U.S. work, the file must have an additional copyright tag indicating the copyright status in the source country. Note: This tag should not be used for sound recordings.PD-1923Public domain in the United States//commons.wikimedia.org/wiki/File:Blockhouse_at_fort_myers.jpg