Composed of over 16 million bricks, Fort Jefferson in Florida is the largest abandoned brick structure in North America

This hexagonal fortress that seems to float on the water is located on Garden Key in the lower Florida Keys within the Dry Tortugas National Park, about 70 miles (110 km) west of the island of Key West. Fort Jefferson (named after the third President, Thomas Jefferson) was designed to be a massive gun platform, impervious to assault, and able to destroy any enemy ships foolhardy enough to come within range of its powerful guns.

Fort Jefferson from the air. Source

It was designed to guard the piracy-prone shipping routes of the Caribbean. The heavy guns, that could fire at ships up to three miles away, were mounted inside the walls in a string of open casemates, or gunrooms, facing outward toward the sea through large openings called embrasures.

Harbor Light at Fort Jefferson. Source

 

Hot Shot Oven at Fort Jefferson. The oven seen here was designed to heat solid cannon shot to be fired at attacking ships. Source

 

Cannon at Fort Jefferson. Source

Construction of the largest masonry fortification ever in the United States began in 1846 on a reef known as Garden Key, and continued for thirty years, but it was never completed. During the years before the Civil War, much of the work of building the fort was done by enslaved laborers. By 1863, during the Civil War, the number of military convicts at Fort Jefferson had increased so significantly that slaves were no longer needed.

More than 16,000,000 bricks were used in the construction of the massive six-sided fort. Source

 

Preserved brick features. Source

 

Lower archways of one interior side. Source

The huge six-sided fort was occupied by Union troops during the Civil War and, due to its remote but strategic location at the entrance to the Gulf of Mexico, was called the “Gibraltar of the Gulf.” Protected by its location from Confederate attack, Fort Jefferson nevertheless remained an important Union post throughout the war.

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Ramparts on the north wall, showing evidence of subsidence. Source

At one point as many as 2,000 lived at the fort, including soldiers, their families, prisoners, laborers, lighthouse keepers and their families, cooks, a civilian doctor and his family, and others.

Granite staircase. Source

 

Magazine & remains of soldiers barracks. Source

The fort remained in federal hands throughout the Civil War. With the end of hostilities in 1865, the fort’s population declined to 1,013, consisting of 486 soldiers or civilians and 527 prisoners and by 1874, the fort had become too expensive to maintain and was no longer a vital part of the maritime defense strategy.

In July of 1865, the fort became the prison for three of the men convicted of involvement in the assassination of President Abraham Lincoln. Source

 

The fort was an active military post until 1874 but remained an important stopping point for military and civilian ships long after that date. Source

Though never attacked, the fort fulfilled its intended role. It helped to protect the peace and prosperity of a young nation. By 1888, the military usefulness of Fort Jefferson had waned, and the cost of maintaining the fort due to the effects of frequent hurricanes and the corrosive and debilitating tropical climate could no longer be justified. In 1888, the Army turned the fort over to the Marine Hospital Service to be operated as a quarantine station.

Interior wall, harbor light, and parade ground. Source

 

Fort Jefferson surrounded by moat. Source

 

On January 4, 1935, President Franklin D. Roosevelt, who visited the area by ship, designated the area as Fort Jefferson National Monument. It was listed on the National Register of Historic Places on November 10, 1970. Fort Jefferson is now part of the Dry Tortugas National Park, which encompasses seven small islands and a whole lot of turquoise-tinted water. Accessible only by seaplane or boat, the fort is one of Florida’s most fascinating heritage attractions.