Arrow Loops allowed castle defenders the ability to fire on attackers from behind the safety the castle walls.
Inside the walls were recessed to allow the archer area to move to better see his targets. This arrow loop has been widened to allow more light into the castle, while stone bars have been added to keep out intruders.
The cross cut allowed a greater area to be covered by the archer.
The stone edging strengthened the wall and the iron bars prevented entry by the enemy.