At the same time there was a change in castle architecture. Until the late 12th century castles generally had few towers; a gateway with few defensive features such as arrowslits or a portcullis; a great keep or donjon, usually square and without arrowslits; and the shape would have been dictated by the lay of the land (the result was often irregular or curvilinear structures). The design of castles was not uniform, but these were features that could be found in a typical castle in the mid-12th century. By the end of the 12th century or the early 13th century, a newly constructed castle could be expected to be polygonal in shape, with towers at the corners to provide enfilading fire for the walls. The towers would have protruded from the walls and featured arrowslits on each level to allow archers to target anyone nearing or at the curtain wall.
At the same time there was a change in castle architecture Until the late 12th century castles generally had few towers; a gateway with few defensive features such as arrowslits or a portcullis; a great keep or donjon, usually square and without arrowslits; and the shape would have been dictated by the lay of the land (the result was often irregular or curvilinear structures). The design of castles was not uniform, but these were features that could be found in a typical castle in the mid-12th century. By the end of the 12th century or the early 13th century, a newly constructed castle could be expected to be polygonal in shape, with towers at the corners to provide enfilading fire for the walls. The towers would have protruded from the walls and featured arrowslits on each level to allow archers to target anyone nearing or at the curtain wall.