Engine blocks too. If you go to a scrap yard though you’ll be pretty amazed at all of the stuff they’ve got collected and sorted. Metal recycling (compared to, say, electronics recycling or plastic recycling) has a very clear economic model and financial incentives. If you’re demolishing a building or scrapping old machinery it will cost significantly less to recycle the metal (because you get paid decently by the pound) than to take it to a landfill (where you pay by the pound instead).