Castles were great defences against the enemy.
However, when gunpowder was
invented the castles stopped being an effective form of defence.
The use of gunpowder made both castles and city walls much more vulnerable
because a cannon could knock down the stone walls.
The only way to knock down
walls before the invention of gunpowder was to dig under the walls to make them
This was a highly dangerous way to do it especially as you might get
boiling hot tar poured over you from above!
See also list of castles
What Is A Castle
List Of Castles