Some of them are encased in steel fiber reinforced concrete. I met a good friend of mine when he responded to an ad I had on CL for concrete tear out. He said he had some atm, he needed to demo. That was all I needed t hear. He got them from a security firm that deals with banks. took my skidsteer with a hydraulic breaker out to his place and busted the concrete off one. Made quick work of it but I cant see how he makes anything doing it. 1/2 inch plate and brass hinges... Guts were gone. I'd charge to remove them...