Always sorry to hear of thefts like this. Provide the local law enforcement agencies with a complete photo of the sign or if you don't have one showing it mounted on the building, find a representative photo for reference. Contact television networks to see if they can provide coverage of this theft and then contact Crime Stoppers in your area to see if they can run an informational ad on radio or TV offering a reward for information. Face Book and second hand shops are also likely locations to check. This serves as a reminder to all collectors with items on display to take the time to create a photographic inventory of your collections, especially those items most vulnerable. : (