around here. There's something in the covers, manganese I think, that keeps them from rusting away. Also makes them more valuable that mere scrap iron. Some years ago, Los Angeles had an epidemic of manhole cover thefts which puzzled the cops. You can't just lift one up and walk away with it! But some crime ring figured it out, with the likely help of a crooked scrap metal buyer. A lawyer I worked for represented a client, a lady who fell down an uncovered manhole. Or at least tripped over it! (I don't think she went all the way down into the sewer.) Anyway, it was an interesting lawsuit against the City who claimed it had no duty to inspect for missing manholes.

Eventually the crooks were caught red-handed or should I say "manhole-handed" and that ended the crime spree.