Forts

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

A tiny island home to a former English slave fort.

Remains of the old fortification along the Western border of the USSR, now an elaborate defense museum.

Site of the 1879 Cheyenne Outbreak and the site where famed Sioux chief Crazy Horse met his fate.

This 19th century granite fortification is one of the most well preserved forts in New England.

A once-stately trading fort is now a ruin slowly being consumed by the sea.

A 19th-century fortress and collection of artifacts offer a tour of Saudi history.

Built to ward off Napoleon's army, this city-sized abandoned Russian fort is now perfect for urban exploration.

A 13th century fortified house built to defend the Duchy of Burgundy.

Built following the War of 1812, this fort has withstood hurricanes for centuries.

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

Wars fought and wars won are remembered by these abandoned bunker ruins.

These ruins in Volvi were once at the intersection of the Eastern and Western Worlds.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

A star fort along the C&O Canal in western Maryland that protected America in three wars.