For a long time, the majority of castles were made from wood. Some were kept in functional state for 4 or 5 centuries!
The majority of ancient castles that survived tooth of time are either destroyed, turned into monuments or converted for public uses. However, some are still inhabited by their original owners. The oldest one is Windsor Castle, home of the Queen Elizabeth II of England. Castles did not have toilets! Waste products were removed in rooms called “garderobes”, with holes that led out of the castle into moats. Average time of castle construction was 10 years. England is currently home of 1500 castle sites, but many more are lost to time. Oldest standing castle in Europe is Château de Doué-la-Fontaine. It was created in 950AD. Largest castle in the world is Prague Castle. It occupies area of 70 000 m². Almost every stairs in the medieval castles were tight clockwise spiral stairs. They were created that way to make combat more difficult for right-handed invaders who had to ascent on those stairs and use their weapons. One of the most famous castle that was built by the Templars during Crusades is Krak des Chevaliers in Syria. Europe was a home of 100 thousand castles. The majority of them is now gone. The word “dungeon” was derived from the word “"donjon” which described central keep of the castle. Because those keeps were dark, cold, and often housed prisoners, the word dungeon was born. At first, castles were built for military and government means. As centuries went on, hostilities subsided, and wealth started to flow during Renaissance, nobility and royalty started to create vanity castles that were used to be summer houses, hunting houses and royal houses. 166 houses and many farming fields were destroyed so that Lincoln Castle could be raised. The most important defenses of Castle are moats, ramparts, high walls, curtain walls, flanking towers, various battlements, machicolations, and gateway defenses. The introduction of gunpowder made castles less secure against attacks. Because of that, the majority of warfare was moved to open fields, leaving castles to be used for other purposes (government centers, prisons, temporary barracks, etc.). The castle that becomes a template for many modern representations of castles in fantasy or medieval fiction is Neuschwanstein, a luxurious 19th-century castle built by Ludwig II of Bavaria. It served as the main inspiration castle of Disney’s “Sleeping Beauty”.