Forts

Once America's longest-manned military fort, now an abandoned hulk.

Held in a fort that once stood for colonization of the area, this museum now tells the history of its indigenous people.

This abandoned fort is said to be the most haunted place in India, so much so that entry is prohibited after sunset.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

A castle-like sea fort from the 17th century is now a museum to oyster farming.

A crumbling island fortress that seems to be covered in a field of stone crosses but is simply incomplete.

An 18th-century Spanish watchtower made entirely of seashell and concrete.

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

A retired military stronghold on the rolling green coast of Donegal.

A centuries-old lookout post still sits atop a natural stone spire.

A man-made island fort that has housed soldiers, scientists, and ravers.

A complex of six forts embedded in the Rajasthan hills.

Final resting place of Geronimo, Quanah Parker, and the first atomic gun ever fired.

A well-preserved 2nd century fort where moles are the archaeologists.

Overgrown ruins of a turn of the century island fort that sees very few visitors.

The second-longest continuous wall on the planet protects a hidden secret in the deserts of India.

A 15th-century granary that played the role of futuristic slave quarters in the world of 'Star Wars.'