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Gibraltar
The legendary geography at the Rock of Gibraltar includes its sheer cliff face, difficult western slope, and location at the southern tip of Europe adjacent to the Strait of Gibraltar. Britain took advantage of this by enhancing medieval structures here, arming and fortifying the top of the rock in the 16th century. Centuries of improvements, including carving tunnels into the rock for armaments, troop movement, and storage, helped Britain to withstand siege attempts. Today the land is still technically a British overseas territory.
A fortress protects and gives military personnel a safe harbor from the enemy. But not all fortresses were created equal. And they certainly weren’t all created the same. Here, Popular Mechanics looks over time and distance to find the 20 most impressive fortresses from around the world and throughout history.