The fundamental importance of cartographic signs in traditional maps is unquestionable, although in the case of multimedia maps their key function is not so obvious. Our aim was to search the problem of cartographic signs as a core of multimedia maps prepared by non-cartographer in on-line Map Services. First, pre-established rules for multimedia map designers were prepared emphasizing the key role of the cartographic signs and habits of Web-users. The comparison of projects completed by a group of designers led us to the general conclusion that a cartographic sign should determine the design of a multimedia map in on-line Map Services. Despite the selection of five different map topics, one may list the general characteristics of the maps with a cartographic sign in the core.