Gary Saul Morson: “The Gulag Archipelago: An Experiment in Literary Investigation, published 50 years ago, was much more than a detailed account compiled from the testimonies of hundreds of people; it was also arguably the 20th century’s greatest piece of nonfiction prose." At the moment I’m thinking that its primary competition for that title is Rebecca West’s Black Lamb and Grey Falcon and Claude Levi-Strauss’s Tristes Tropiques.