There are no monolith on this area.
It’s located on the same room where you find the discovery point “A Hoard of Ritual Sword”
==The Crest of Innominat==
When you arrive at Artorius Throne, keep going northwest. You will arrive on the small room with this discovery.
==A Hoard of Ritual Sword==
It’s on the same area as the Crest of Innominat. However, you can’t reach it immediately, you need to to venture the dungeon so you can get access into this room (after the wind room;CMIIW).