The analysis starts with the observation that the presence of a fireplace, situated either internally or externally, is a criterion which often influences the religious interpretation of cult sites in Thrace in the Archaic and Classical periods. This premise is tested using two case studies, focusing on sites identified as places of worship based on the presence of an interior hearth. These examples are then compared to the cult areas of Greek cities in the North Aegean region which include buildings fitted with interior fixed hearths, and, also, to the domestic structures of Olynthus. The study demonstrates that the function of a hearth can be accurately determined through a combined examination of its structure, associated artefacts or furniture and its context of discovery. This exercise confirms that we have the means to distinguish hearths from altars archaeologically. Indeed, while the latter are used for the deposition and consumption of offerings, these hearths are also sometimes used to cook, but also serve to heat or light a room. Therefore, the associated room can both serve as a meeting place, in a general sense, while also facilitating the more occasional function of commensality. The study highlights the criteria which make it possible to distinguish these different uses of hearths in ritual and domestic contexts.