What are some of the greatest fortresses ever built (they have been successful in repelling invaders and/or are impressive in terms of their size and ingenuity)? - Quora

What are some of the greatest fortresses ever built (they have been successful in repelling invaders and/or are impressive in terms of their size and ingenuity)? - Quora

What are some benefits of having a fort or a fortress? - Quora

What are some of the greatest fortresses ever built (they have been successful in repelling invaders and/or are impressive in terms of their size and ingenuity)? - Quora

The World's 30 Most Impressive Fortresses

What are some of the greatest fortresses ever built (they have been successful in repelling invaders and/or are impressive in terms of their size and ingenuity)? - Quora

What is an example of a fortress or castle that people would not expect to be there and why? - Quora

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

What are some of the greatest fortresses ever built (they have been successful in repelling invaders and/or are impressive in terms of their size and ingenuity)? - Quora

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

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

What are some of the greatest fortresses ever built (they have been successful in repelling invaders and/or are impressive in terms of their size and ingenuity)? - Quora

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

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

What are the most impenetrable castles in the history of Great Britain? - Quora