This article is fascinating, and it has a great quote about the 75-mile "landscraper":

The concept carried echoes of an idea originated in the 1960s by Superstudio, an Italian architectural collective, for a structure so enormous it would wrap around the entire planet. This “Continuous Monument” was never a real building proposal; it was intended as a critique of excessive urbanization and of the modernist megaprojects then in vogue. One of Superstudio’s last surviving members, when asked about the Line by the New York Times, dryly noted that “seeing the dystopias of your own imagination being created is not the best thing you could wish for.”