Some towers have survived. If you are lucky, you will be able to go up one and see the spiral staircase.
If you can, imagine this: you are under attack and the attackers have reached the stairs. You are near the bottom of the stairs, sword in right hand.
The attackers are climbing the stairs, but their right (sword) hand is against the central pillar of the stairs. Try a reconstruction to see how this helped you, as defender.
