Cultural heritage is typically not on the people's top lists when searching for entertainment activities. Publicized temporary exhibitions can draw many visitors to a museum, urged by the opportunity of seeing certain items, but in general there are no particular stimuli and the visits are postponed once and again, if not forever. In this paper, we argue that it is possible to instigate curiosity in relation to dates, periods and events that are relevant to the potential visitors and connected to the cultural heritage items in direct or subtle ways. Likewise, proper reasoning about dates can improve the experiences of actual visitors, by promoting serendipitous learning, increasing retention and revealing that subsequent visits may drive them around the venue following new appealing narratives. We present the outline of a recommender system grounded on rich semantic modeling of relevant dates in the user profiles, in the cultural heritage knowledge bases and in an almanac of important days, connected to keywords and/or historical events and characters. We also explain how this system is going to be used in the pilot experiments of the CROSSCULT EU project, starting in September 2017.