What is this thing in my build?

Recently completed Arkham Asylum and the X Mansion and both of them came with this small cardboard box looking thing. I googled it, but couldn’t find anything. Anyone know what it’s supposed to represent or what purpose it serves? Both of them are placed behind the buildings in the back alleyway areas, and they have stickers. I put my Arkham Asylum on display already so I don’t want to pull it down to show this one piece, this is the x mansion one with a Trask Industries sticker on it. ...