Powell's Books, 1918
After some damage repair to the roof at Powell's City of Books exposed some old signs on a couple roof beams (noted here and here), they've finally completed work. Fortunately, they've left the signs, dating to when this housed a car dealership, intact. The "Parts Dept." sign even has a nifty little finger pointing downward.
Powell's City of Books is at NW 10th and Burnside. The beams are in the Blue Room and if you stand on the stairs between the Blue and Yellow Rooms you can see both signs.