Roden Crater, Arizona

An extinct volcano, composed of red and black cinders, on the edge of the Painted Desert, which is being turned into a monumental work of land art by the artist James Turrell. The project has been under construction for over 25 years, since Turrell's acquisition of the crater in 1977. As of 2016, six of a projected 21 viewing spaces have been completed, including the reshaping of the bowl of the crater itself. Some tunnels have been added as well, including one that is 854 feet long. Visitation will most likely be limited to a few people at a time, staying overnight at the site.