Go behind the stone structure and jump to grab the handhold on the pillar (there are handholds to both sides, so it does not matter which way you go).

Climb to the top of the pillar until you reach the handhold that goes around it.

Traverse around the corner to reach the side of the pillar outside the bars. For example, if you climbed up the left side of the pillar, traverse around the left corner. Jump to grab the top ledge of the pillar and pull up.

Go to the other side and use the Grapple to catch the metal ring above. Swing across and press Jump to leap off and land in the hallway behind the door.