Why Fort Jefferson
Fort Jefferson is a historic military coastal fortification located on Garden Key within Dry Tortugas National Park, 68 miles west of Key West, Florida. Spanning 16 acres, this six-sided fortress was constructed with more than 16 million bricks, making it the largest brick masonry structure in the Americas. Among military forts in the United States, only Fort Monroe in Virginia and Fort Adams in Rhode Island occupy a larger total footprint.
Initial military surveys of the Dry Tortugas in the 1820s deemed the sandy keys unsuitable for naval installations. However, a whitewashed brick lighthouse was erected on Garden Key between 1825 and 1826 to guide shipping around local reefs. Subsequent evaluations highlighted the strategic value of the anchorage for defending Gulf Coast shipping lanes, leading to the site becoming a military reservation. Construction of the fort began in December 1846, enclosing the existing lighthouse within its walls. The labor force relied heavily on contract workers and enslaved labor until 1863. A new metal light tower was mounted on an outer wall in 1876, after which the original brick lighthouse was dismantled in 1877.
The fort's architecture features two tiers of casemates surrounding a 13-acre parade ground. Corner bastions contain gunrooms, gunpowder magazines, and granite spiral staircases, while heavy guns were positioned facing outward toward the sea. Within the central grounds lie headquarters, a hospital, officer quarters, and three large barracks. To supply fresh water on an island without natural resources, engineers built an extensive wall cistern system designed to collect rainwater filtered through sand-filled columns, supplemented during the Civil War by steam water condensers.
Union forces controlled the fort during the Civil War, utilizing it as a military prison for convicts and individuals involved in the assassination of President Abraham Lincoln. Following recurring yellow fever outbreaks, severe storm damage, and eventual military departure, the installation served at various times as a quarantine facility, a naval coaling station, and a wireless communications site during World War I. Structural renovation and historic preservation work were undertaken by the Works Progress Administration during the late 1930s.
Today, Fort Jefferson is preserved as part of the national park system and is listed on the National Register of Historic Places. Visitors can access Garden Key via daily ferry service from Key West, chartered seaplanes, or private boats. On-site facilities include a museum and a bookstore, and primitive camping is permitted along the beach.
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