What are some of the best fortified historical fortresses in your opinion? - Quora

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

What would the closest thing to a perfect late medieval castle look like? - Quora

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

What are some beautiful medieval castles? - Quora

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

What medieval castle had the most impressive defence? - Quora

Could a modern military successfully invade and capture one of the castles or strongholds that were built during medieval times? - Quora

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

What are some of the best fortified historical fortresses in your opinion? - Quora

The World's 30 Most Impressive Fortresses

What were the most unique castles during medieval times? - Quora

What are some of the most imposing castles around the world? - Quora

What type of defensive structures (walls, enclosures, forts, etc) did Native Americans build? - Quora