Physical changes to the Castle over time
-Rebuilt in stone 1150 to 1180
-3 metre thick curtain walls (to defend against Trebuchets)
-Barbican (8 metre high wall built on both sides of the road, could drop boiling oil from here) added to gatehouse (to defend against battering rams)
-Mill built (soldiers had the facilities to produce wheat and flour to outlast any siege, especially during 1173 and 74)
-Pele yard added to garrison troops
-Arrow loops added to walls
-1200s two D shaped towers added to gatehouse