 His 1879 journey to the site of Troy is described in "Beiträge zur Landeskunde in Troas" ("Contributions to the knowledge of the landscape in Troy", 1879) and "Alttrojanische Gräber und Schädel" ("Old Trojan graves and skulls", 1882).Virchow was an opponent of Darwin's theory of evolution, and particularly skeptical of the emergent thesis of human evolution.On 22 September 1877, he delivered a public address entitled ""The Freedom of Science in the Modern State"" before the Congress of German Naturalist and Physicians in Munich.