This artifact is found in the Western portion of the Catacombs. Using either the Northern or Eastern entrance, you will need to head over to the Central part of the Western portion.
Once there you will want to head across the Wooden bridge toward the pillar. Jump off to the Northern side and then continue to the West. Make your way up toward the next room. Turn to the left and swing over to the next landing.
Take the stairs up and head through the door at the top. Turn toward the Northern wall. You will see the artifact close to the ceiling of this room.