In order to complete the Platinum trophy in Assassin's Creed Valhalla, you will need to collect all the artifacts found in each region of Norway and England.
Here are all the locations of the artifacts in the region of Oxenefordscire.
Roman Artifact — Evinghou Tower
There's a moveable shelf that leads to the artifact, but it will be initially blocked.
Go right, climb the small cliff, and an opening will allow you pass through. Here you'll find a grate preventing you from going further.
Shoot the pots through the grate, and return to the shelf, which you can now move. The artifact will be waiting.
Cursed Symbol — Southwest of St. Albane's Abbey
Access will be blocked by a destructible wall. If you have the Incendiary Powder Trap ability (found inside the Easten Church in Walden, Grantebridgescire), you can use this to destroy the wall quickly.
If not, you'll have to find one in a roundabout way. Take the path left of the wall, where you'll find a zipline. You'll land on the second small island found in the middle of the lake, and conveniently, right next to some fire pots. However, this is where the hard part begins — getting it back to the wall without destroying it.
Looking north, you'll see a rope across the water. Head across — carefully! — and then traverse the platforms to your left. There's another rope here, and while parts of it are underwater, you'll be able to cross it unscathed. Leap across the semi-submerged rooftop and across to the next roof (which appears just under the water).
Use the raft as a stepping stone, then across the poles to the left. There's another rope here, you'll need to look down to see it. You'll hop across to another rope automatically, and when you reach the pole at the top, there's a log to the left you can use. This brings you back to the first island.
Now, simply destroy the wall and shoot the symbol.
Roman Artifact — Near St. Albane's Abbey
This one is found in a ruin slightly southwest of the Abbey, underneath a breakable section of the floor.
Grab a fire pot from the Abbey, and make sure you arrive with the thing intact. There's a chance you'll be jumped along the way, which won't help at all.
When you succeed, break the floor and claim your bounty.
Cursed Object — East of Thaerelea Ruins
You'll pass through the narrow gap to enter a cavern. Here, turn right and pick up a fire pot. Be careful here, as there's a whole lot of flammable gas. To clear it, light your torch and throw it from a safe distance.
Continue down the passageway with your fire pot. There'll be a couple more areas full of gas to clear, then some obstructions to dispose of.
Break the wall, then destroy the Cursed Object with your bow.
Roman Artifact — North of Perie
You'll find a locked door North of Perie. Use Odin's Sight, you'll see a pile of stones to the left of the door: they key is his hidden in it.
Move aside the stones, get the key and open the door. The Roman Artifact is on the table just inside.
Roman Artifact — North of Buckingham
The artifact is hidden below the ruins. You'll have to destroy the rubble blocking the hole. Go across the street: there are fire pots on the platform above. Climb up, pick up a pot and make your way back across the rope.
Once you reach the top pillar, jump left to the higher pillar in order to hit the rubble with the pot.
The artifact is inside the hole on a table.
Flying Papers — Buckingham
The paper is above the longhouse. Simply follow the paper until you catch it.
Cursed Symbol — South of Buckingham
The artifact is in a pit in front of two burning effigies. The pit is filled with a flammable and poisonous gas. Light your torch and throw it in the pit in order to disperse the gas. Go down and follow the path, you'll find a breakable floor. Break the floor with an arrow then drop down again.
Then, destroy the artifact behind you.
Rigsogur Fragment — North of the Derelict Shrine of Camulus
The artifact is in the longboat that Alvar is building.
Flying Papers — Oxenforda
The paper is above a little house with a chimney. Simply follow the paper until you can catch it.
Roman Artifact — Southeast of Oxenforda
You'll find a barred door southeast of Oxenforda. Go to the south of the door and you’ll see grates in the ground. Follow the grates until you face a Roman statue wearing an ivy wreath and you'll find the entrance of the hole. Jump in the hole and shift the mobile barrier.
Break down the door and climb up to the artifact location.
Treasure Hoard Map — North of Lunden, Hammeham
There's a boarded well in Hammeham. Break the lid and drop down, the map is on the floor.
