Flying Paper - 1
At the western part of Jorvik, over the river. Northeast of the Jorvik Theatre.
Follow the Flying Paper and catch it!
Reward: Vegvisir Scheme (Back)
Flying Paper - 2
Between the Councillor's House and Coppergate Market.
Catch the Flying Paper!
Reward: Vegvisir Scheme (Front)
North of the Eboracum Sewers and southeast of The Minister.
Climb one of the pillars to get to the Artifact.
Royal Hall - East
East of Royal Hall, at the base of the big bridge, is a weak wall / stone barricade that requires an oil jar.
You can get Oil Jars at the waterside at the other side of the river (see screenshot).
Use a boat to get an oil jar to the weak wall.
Treasure Hoard Map
Inside the Minster, you can move a stone shelf to access the room behind the altar.
The stone shelf is near one of the entrance doors.
Second set of screenshots shows the treasure look location.