Forts

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.'

Fighting the British and making game shows for over 150 years.

Twenty-year effort to raise a castle using tools and techniques from the 13th century is now abandoned in the Arkansas woods.

Surreal riveted sea forts once protected the Kent shores from German attack.

A nearly unconquerable island-fort in the Indian Ocean.