Take the path to the right from Lord's Watch to reach Giant's Husk.
Head across to the stairs opposite the entrance to the area.
Continue to the top floor and jump to the platform that leads to the shipping containers.
Hop over to the other side and go straight towards the red shipping container opposite.
As you approach, a marker will pop up to the right of it.
Head into the gap between the containers and you'll find the medallion on the ground.