https://www.newyorker.com/magazine/2016/08/29/michael-heizers-city

The use of valueless materials is strategic, a hedge against what he sees as inevitable future social unrest. “My good friend Richard Serra is building out of military-grade steel,” he says. “That stuff will all get melted down. Why do I think that? Incans, Olmecs, Aztecs—their finest works of art were all pillaged, razed, broken apart, and their gold was melted down. When they come out here to fuck my ‘City’ sculpture up, they’ll realize it takes more energy to wreck it than it’s worth.”