While I applaud this idea, Please Please Please, do not put adhesive stickers on buildings, vacant or not, even if other people already have put stickers or posters on them. Adhesive is really hard to get off buildings without damaging the surface to which it's stuck. People with good intentions, coming later, often use harsh methods like sandblasting or pressure washing to remove the remnants of adhesive and paper -- doing even more damage to the building materials underneath. The same thing goes for metal signs, lamp posts, etc. Just say no to stickers. A small piece of tape will do much less damage. Thanks.