There are 13 Relic Artifacts in Washington. Here's where they are:
1 | Abraham Lincoln's Top Hat
This Relic can be found at West Potomac Park on the top of a statue.
2 | Lewis and Clark Pocket Compass
This Relic can be found at Southwest. Inside the building behind the desk.
3 | Old Glory Flag
This Relic can be found at East Mall.
To be able to enter the building you have to pick up the Side Mission "Missing Curators". The Mission Giver is close to the JTF Comm "Georgetown Patrol".
Once inside the building. The relic is in the statue room.
4 | Plymouth Rock Fragment
This Relic can be found at Judiciary Square.
You can only enter when and after the "Judiciary Square Metro Station" Side Mission given by the Drone Operator at the White house.
Then, it's in a room at metro level.
4 | The Bill of Rights
This Relic can be found at West Potomac in the Washington Monument Control Point Storage Room
5 | Crystal Skull
This relic can be found outside, south of the Final Epiphany Safe House at Downtown East
6 | Teddy Roosevelt's Teddy Bear
This relic can be found at West End.
This area is only accessible through the Side Mission: "Historic District Attack"
The mission is unlocked after fully upgrading the Campus Settlement
It's inside the building where the civilians are hiding.
7 | Yamaki Pine
This relic can be found at Foggy Bottom.
From the road side, there is a big white truck next to a locked up fence. Climb up the truck, shoot the lock on the door. Then you can go through the door, use the rope to get up. The Relic is on the other side.
8 | Lincoln's Pocket Watch
This relic can be found at West Potomac Park.
Use one of the manholes south east of the Lincoln Memorial to get into the sewers.
9 | Greffuhle Stradivarius
This Relic can be found at Downtown West. South of the Settlement, there is also an SHD Cache.
Go inside the alley of the building block. There you can climb into the apartment.
10 | Thomas Jefferson's Polygraph
This Relic can be found at Constitution Hall.
It's inside the prison.
Best way to pick it up while doing the "Outcast Work Camp" Side Mission. You'll run straight into it.