Excalibur

"Only he who could extract 'Excalibur' from the rock would become the legitimate king of England." Merlin the Wizard. The first challenge will be to place it in the rock. It really isn't complicated to extract it if one could see the labyrinth. The problem is that it is hidden by the rock, and we are blind. I leave a skeleton of the outer ring, which allows visualizing the ring for practice, in case inserting the sword Excalibur into the stone becomes complicated. Enjoy!