US military bases have long been the training grounds for some of the world’s finest soldiers. But as threats evolve and technology advances, some installations become obsolete and are decommissioned. While a few find new life in the civilian world, others are left to decay, reclaimed by nature and time.

From forgotten forts to Cold War relics, explore America’s eeriest abandoned military bases and the secrets they still hold…

Fort Jefferson in the Florida Keys began construction in 1846 and was intended to help protect American shipping lanes in the Caribbean from piracy and enemy attack. The sturdy, six-sided brick walls protected living quarters where soldiers and equipment were stored, surrounded by a moat.

When the American Civil War started the fort was used as a prison – mainly for Union deserters. Today it is part of the Dry Tortugas National Park and remains the largest masonry structure in the Americas, covering 16 acres.

When it was built in 1942 to protect America’s East Coast from possible attack by Nazi Germany, the Cape May Bunker sat on high ground 900 feet (275m) or more from the waterline and was covered in sod to blend in.

Today it sits abandoned and exposed, the changing tides washing against the sturdy wooden pilings it sits on. The round concrete turrets on either side once housed six-inch guns, but these days the emplacement is neither safe to visit nor easily accessible.

The Stanley R Mickelsen Safeguard Complex in Nekoma, North Dakota was the United States' only operational ABM (anti-ballistic missile) defence system, designed to intercept and destroy incoming Russian missiles.

While it was operational for less than a year, its very existence encouraged the Soviets to sign the Anti-Ballistic Missile Treaty in 1972. Despite costing $6 billion (£5.3bn) to build, the underground complex was flooded when the site closed, with only the eerie launch pyramid still visible.

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Fort Ord is a former US Army post on Monterey Bay on California’s Pacific coast. It was primarily a training centre, and as many as 1.5 million soldiers passed through the base from the beginning of World War I through to Operation Desert Storm in 1991.

The base was closed in 1994, and in 2012 President Obama proclaimed the land the Fort Ord National Monument. While it remains largely abandoned, parts of the site have been repurposed for public use, including the national monument and educational institutions.

Fort Tilden was established in Queens in 1917 to protect the entrance to New York Harbour, its giant cannons pointing towards the sea, ready for action. Despite being reinforced with concrete during World War II, the fort never saw action and was eventually decommissioned in 1974.

Today, it is part of the Gateway National Recreation Area and is managed by the National Park Service. While some areas have been repurposed for athletic fields and hiking trails, much of the fort's military infrastructure remains abandoned, with crumbling bunkers and overgrown batteries scattered throughout the site.

The Devil's Slide Bunker on the shores of San Mateo County in California is what's left of a triangulation station and observation site that saw use during World War II, and was once part of a much larger complex of buildings.

The entire site was abandoned in 1949 and today a solitary bunker remains atop the promontory. It's now privately owned, but that has not stopped graffiti artists from tagging the edifice.

Construction of this hexagonal fort in the middle of the Patapsco River just south of Baltimore began in 1848 but never finished. Robert E Lee, the future commander of the Confederate Army in the American Civil War, supervised the project for a time, but grew impatient and accepted a position at the West Point military academy in 1851.

In 1864, heavy rains flooded the island, showing that it was unsuitable for storing weapons, and in 1920 it was abandoned. Today the only visitors are urban explorers and the birds that nest in the fort's trees.

Tucked 720 feet (220m) into the hillside beneath the luxurious Greenbrier Resort in White Sulphur Springs, West Virginia, lies a heavily fortified bunker, secretly constructed between 1958 and 1961 as a Cold War-era emergency shelter for Congress in the event of nuclear war.

After the classified facility was exposed by The Washington Post in 1992 it was decommissioned, and repurposed as a data storage facility. Today, a portion of the bunker, still safeguarded by gigantic blast doors, is open to the public and can be explored on a 90-minute guided tour.

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The Bong Air Force Base in Wisconsin is the US military base that never was. It was abandoned in 1959 just three days before concrete was to be poured for a 12,500-foot (3,800m) runway. A heating plant was one of the few buildings completed, and you can see it here with Colonel Charles E Lancaster, commander of the base.

At the time of cancellation, four years of work and more than $29 million (£22.8m) had gone into the project. Today the site forms the Richard Bong State Recreation Area, a popular fishing and hiking spot. The gravel runway is still visible.

Built between 1819 and 1828, Fort Pike was constructed to defend New Orleans from a potential naval invasion. During its tumultuous history, the fort served as a prison during the Second Seminole War (1835–1842), where more than 1,000 Indigenous Seminole people and their allies were held before being forcibly relocated.

Over the years, Fort Pike suffered damage from storms including Hurricanes Katrina (2005) and Isaac (2012). The extensive destruction led to its permanent closure in 2015. Today, it remains abandoned, with its crumbling structure slowly being reclaimed by nature.

Set in the Bering Sea at the western edge of Alaska’s Aleutian Islands, Adak Army Airfield was built in 1942 to counter the Japanese-held base at Kiska Harbor. Later, it became a key Cold War outpost, but its strategic importance faded after the Soviet Union collapsed.

Decommissioned in 1997, the 47,271-acre site was transferred in 2004 to the Aleut Corporation and the Alaska Department of Transportation. While much of the former military base remains abandoned, the airfield still operates as Adak Airport, serving the island’s small civilian population.

Known as 'the Gibraltar of the Chesapeake', Fort Monroe was built between 1819 and 1834 to guard Chesapeake Bay and Hampton Roads. The largest stone fort ever built in the US, it played a key role from the Civil War through to the 20th century, and hosted 14 US presidents, from Andrew Jackson to Harry Truman.

Though decommissioned in 2011, Fort Monroe remains active as a national monument, managed by the National Park Service. Visitors can explore its historic buildings and museums, while ghost stories linger – some say the spirits of Abraham Lincoln, Ulysses S. Grant and Edgar Allan Poe still roam its halls.

Chanute Air Force Base is a decommissioned US Air Force facility about 110 miles (180km) south of Chicago. It began as a pilot training school towards the end of World War I, and before its closure in 1993 was one of the oldest Air Force facilities in the country.

Since then, buildings like the former mess hall (pictured) have lain abandoned, although in 2006 much of the base was placed on the National Register of Historic Places.

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Carlstrom Field in Arcadia, Florida, was originally established in 1917 as a World War I pilot training base and later used during World War II before being decommissioned.

Over the years, the site was repurposed for various civilian uses, including serving as a juvenile detention facility until its closure in 2019. While some structures remain, much of the area is now overgrown and deteriorating. 

Constructed between 1897 and 1901 to defend the shores of south Baltimore, Fort Armistead was operational for less than two decades after most of the artillery was removed for use overseas when the United States entered World War I in 1917.

Today, the fort serves as a local park, with its sturdy fortifications engulfed by nature and vast quantities of graffiti. Head to the Battery Irons Entrance (pictured) to explore its eerie tunnels... if you dare.

Fort McClellan was an army base in Alabama that opened in 1917 and closed in 1999 as part of the Base Realignment and Closure programme. It was a massive training camp during World War II, training almost half a million troops over the course of the war, and served as a prisoner of war camp.

At various points it housed the Military Police Corps, the Women's Army Corps (pictured) and the Chemical Corps, and when the base was decommissioned contamination from chemicals and smoke training had to be cleared. Much of the land has now been repurposed, although concern lingers that some people who served there may have been exposed to low levels of hazardous chemicals.

Fort Worden is one of five seacoast fortifications started in the Puget Sound region in 1897 to protect the navy base at Bremerton. At its height it boasted 41 guns mounted in 12 batteries, and it was an active military installation until 1953.

In 1973 the base was turned into a multi-use state park with long empty beaches, a picturesque lighthouse and spooky old military batteries to discover. Battery Kinzie (pictured), built to house artillery but now covered with moss, is perhaps the most interesting to explore.

Fort Snelling sits on the bluffs overlooking the confluence of the Minnesota and Mississippi Rivers. Completed in 1825, the fort became notorious prior to the Civil War when soldiers stationed there were allowed to bring enslaved people with them, even though slavery was prohibited in the surrounding territory.

The famous Round Tower (pictured), one of the first buildings to be constructed, remains an impressive sight. Local lore holds that Count Ferdinand von Zeppelin, founder of the Zeppelin airship company, launched his first balloon flight from the top of the tower while staying there as a German military attaché during the Civil War. There is sadly no evidence to support this claim.

Deep in rural eastern Washington, remnants of three Cold War-era missile silos stand as eerie relics of a bygone era. These silos once housed Titan I intercontinental ballistic missiles (ICBMs), part of America’s early nuclear deterrent programme. The Titan I system was operational for only three years (1962–1965) before being decommissioned and abandoned.

Today, the flooded silos have become an unusual dive site, drawing adventurous divers to explore their submerged tunnels and control rooms. Local dive company Undersea Adventures has previously offered guided dives, though access is highly restricted. Due to extreme hazards such as entanglement risks, collapsing structures and limited visibility, attempting to explore the site alone is highly dangerous and strongly discouraged.

Built between 1819 and 1834, the pentagon-shaped Fort Morgan stands guard over Mobile Bay on Alabama’s Gulf Coast. It remained an active military post until World War II and played a pivotal role in the Battle of Mobile Bay during the Civil War.

Now a historic site managed by the Alabama Historical Commission, Fort Morgan is open to the public, though it has faced challenges from hurricane damage, with ongoing restoration efforts. Some say the fort's past lingers – visitors have reported shadowy figures and phantom voices, believed to be the spirits of former soldiers.

Fort Stevens in northern Oregon was built during the Civil War to guard the mouth of the Columbia River. On 21 June 1942 it became the only military installation in the contiguous United States to be shelled by an enemy during time of war since the War of 1812, when it suffered a surprise attack from a Japanese submarine.

Today, it is a state park and marks the northernmost stop on the beautiful Oregon Coast Trail. During the summer visitors can take an underground tour of the gun battery that served as a World War II command centre.

Fort Wolters began its life as a Texas National Guard training camp before being officially turned over to the US Army in March 1941. It became an enormous US Army training facility during World War II – its troop capacity peaked at nearly 25,000 – and during the Vietnam War it trained helicopter pilots.

After being deactivated in 1975, parts of the base were turned into an industrial park. And in 1998 a small part of the former base was turned into the Fort Wolters Historical Park.

Saint Helena Island is perhaps best known as a major centre of African-American Gullah culture. But visitors digging a little deeper may stumble upon the remains of Fort Fremont, abandoned and draped in Spanish moss, and one of only two coastal fortifications to have survived intact from the Spanish-American War. Once a sprawling complex with a barracks, mess hall, hospital and stables, now only the mouldy bastions and a few shadowy tunnels remain.

Construction began on Fort Gorges in 1858 in order to protect Portland harbour. But by the time it was finished in 1864 it was already obsolete, as the cannon holds were too small for modern guns. 

It was briefly brought back into service during World War II as storage space for submarine mines, but has since been abandoned and left to decay. Today, it sits despondently in the Atlantic Ocean's Casco Bay, sprouting greenery from its ramparts.

Now discover the intriguing abandoned places you can visit in every US state