This article focuses on radiocarbon (14C) dating of the organic matter (OM) of natural-anthropogenic objects—the cultural layers (CLs) of archaeological sites. Using examples from three ancient sites located within the European part of Russia, in southern taiga and forest-steppe natural zones, we demonstrate approaches to the interpretation of 14C dating of OM derived from the organomineral material of the CLs studied. We use the term “archaeological humus” as defined as the OM formed within the CL from “anthropogenic matter” (i.e., organic residues that were produced during the past human occupation of the site) without or with negligible contribution of OM inherited from pre-anthropogenic stages of pedogenesis. The archaeological humus is formed within closed or semi-closed systems by the processes of humification and physical stabilization of OM. The use of hierarchical (from macro- to submicro-) morphological investigations at one of the sites (Gnezdovo) combined with 14C dating allowed conclusions to be drawn about the age of formation of different OM components in CLs.