Are you familiar with "fire marks", or "fire insurance marks"? They were plaques, most often made of cast iron, that were attached to the front of a home or commercial building to indicate that the owner had fire insurance. Years ago, (we're talking nineteenth century), fire brigades were commonly owned by insurance companies. When they responded to a fire, building owners wanted to make sure the brigade knew they were covered by insurance. It was thought that uninsured dwellings would be left to burn, although that probably wasn't true. Leaving structures to burn would have jeopardized other insured buildings, and there is little historical evidence of fire brigades ignoring the uninsured.
An original fire mark from the late 1700's to 1800's is a real find. They are valued in the hundreds of dollars. Most of the fire marks you will find now are nostalgic reproductions made in the 1950's when the colonial look was popular. Still, these are collectible in their own right and have some value. I just purchased the fire mark (below) and I'm pricing it at $45: