What are/have been the most impregnable fortresses in history? - Quora

What are/have been the most impregnable fortresses in history? - Quora

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Suppose that the Russians had the technology to build Western European castles, could they stop the Mongols in 1236? - Quora

What was the most well thought out medieval castle in terms of defense and defender survivability? - Quora

What are/have been the most impregnable fortresses in history? - Quora

Which castles, other than Alnwick Castle, have been prominently featured in movies? - Quora

How would you design the most impenetrable medieval fortress? - Quora

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What is the coolest castle in history that is known to have existed? - Quora

At what point in history were castles the best built and strongest? - Quora

What are/have been the most impregnable fortresses in history? - Quora

Which is the strongest Fort in the world? - Quora

What is/was the strongest fort/castle for defense from any era, preferably not English style? - Quora

What is/was the strongest fort/castle for defense from any era, preferably not English style? - Quora