Guide:
Northwester central part of Cyrodiil, between Fort Aleswell (to the northeast) and Fort Ash (to the Southwest).
This hidden collectible can be found near Empire Tower POI. Follow the road that leads uphill until you reach a tall wrecked tower. Fight through nearby hostile Rock Bone creatures and go upstairs to the upper level of the tower. Rock Bones will be waiting for you on tower stairs as well. Be careful, and don’t rush because you can easily die. Skyshard on the top of the tower is next to the “Spirit of the Daedra” lorebook.