This volume is dedicated to the memory of the outstanding humanities scholar Leo S. (Lev Samuilovich) Klejn (1927–2019). A short biographical essay provides an overview of the main landmarks of Klejn’s life and the main stages of his scholarly and pedagogical career. The articles included in the volume reflect a wide range of Klejn’s scholarly interests and his contributions to the fields of theoretical archaeology, history of science, and to the study of a whole number of archaeological cultures from the Neolithic through the Middle Ages. A number of articles deal with Klejn as a field archaeologist, a philologist, a semiotician and an art historian. Particular attention is given to his pedagogical and public activity. A short memoir of Klejn’s adopted son Damir characterizes him as a person. The appendix contains a full list of Klejn’s publications and of main publications about him. The book is designed for a wide range of researchers in the humanities (archaeologists, historians, ethnographers) and experts in allied subjects, humanities degree students, and all readers interested in humanitarian knowledge in general.