Walls

The little-known second castle that William the Conqueror built in York.

This whimsical outsider art wall holds tiny treasures donated by the local community.

The ruins of a massive World War I fort overlook the border between Zambia and Tanzania.

Scotland still bears an enormous scar of its Roman past.

Climb a set of vertiginous stone steps to the top of this impressive ancient edifice.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

The only surviving piece of Copenhagen's 16th-century defensive wall.

Part of an abandoned19th-century fortress hides in plain sight inside a modern office building.

These ruins witnessed the final gathering of the failed Jacobite Rebellion.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

These barriers stand as stark reminders of Northern Ireland's troubled past.

A catapult rock from Gotland’s 13th-century civil war is still lodged in Scandinavia's best-preserved medieval city wall.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

Ancient barriers wrap around what was once an important stop along the Silk Road.

These brass bunnies honor the rabbits that dominated the no-man's-land around the Berlin Wall.

Paleoamericans built these ancient walls high in the Colorado Rockies as part of an extensive hunting system.