Why Castles Have Round Towers and Tall Walls

Long ago, a king in France built a castle called Chateau Gaillard in just two years. It sat high on a cliff over a river, with thick round towers and three rings of walls. Enemies looked at it and thought, 'We can never get inside that!' That was the whole point. Castles were giant stone puzzles built to keep people safe.

- Why castles were built of stone instead of wood - Why towers are round instead of square - What a moat and a drawbridge do - Who lived and worked inside a real castle

The very first castles, built around 1000 years ago, were made of wood on top of a big dirt hill called a motte. Wood burns fast! Attackers just shot flaming arrows at it. So builders switched to thick stone walls, sometimes 10 feet wide — that's wider than a school bus is tall standing on its end. Stone does not burn, and it is very hard to knock down.

Early castles had square towers. But attackers found the square corners were weak — they could dig underneath a corner and the whole tower would crack and fall. Builders then made towers round. A round tower has no corner to dig under, and it lets guards see and shoot arrows in every direction with no blind spot. That is why Chateau Gaillard's towers were round.

A moat is a deep ditch, often filled with water, dug all the way around the castle. It stops attackers from bringing ladders or towers close to the walls. The only way across was a drawbridge, a wooden bridge that guards could pull up using chains. Right above the front gate, castles often had small holes in the ceiling called machicolations — nicknamed 'murder holes' — where guards could drop rocks or pour hot sand on anyone trying to break through the door below.