According to a report in Las Vegas Weekly, the  Conservation Lands Foundation is pushing to make a project by land artist Michael Heizer, of “Levitated Mass” fame, a national monument. The newly threatened City installation is a still-incomplete collection of giant abstract structures stretching for more than a mile into the Nevada Desert.

The move came after the failure of Nevada Senator Harry Reid’s Garden Valley Withdrawal Act, attempting to keep the land—and more than 800,000 square miles of adjacent federal property in Garden Valley—free from mining. Critics have complained that it’s a convenient tool in the effort to keep the area free of industrial activity, but conservationists argue that the unspoiled area as a whole is worth saving.

“These are two of the most scenic valleys in Nevada, two of the most undisturbed, least-roaded, and least populated portions of the state and therefore the country,” Brian O’Donnell, executive director of the Conservation Lands Foundation, told Las Vegas Review Journal.

Heizer, who has been working on the piece since the 1970s, plans to open it to the public once it’s complete. Made of dirt, rocks, and concrete, City considered by some to be the largest piece of land art in the world. But since the artist hasn’t allowed visitors, many assertions about the piece remain unclear.