I came across some neat old metal signs that I use in my haunt. One says to wear your rubber boots when walking through the hog lot ,so you don't spread disease. (The Government Says So!)
Somebody used it for target practice but the rusty bullet holes give it "Character" (Bullet holes for a Zombie sign might be good?)
The other old sign was popular when I was a kid. It had the symbol for radiation and tells you there is a fallout shelter on the property.
Maybe the wine cellar could qualify?