Based on a case-study where the Museum of National Antiquities in Stockholm, Sweden was extended to an archaeological excavation site, this paper addresses the potential for increased public access to cultural heritage sites by means of video mediated communications and outreach activities. A recently formed interdisciplinary research group representing skills in designing mediated environments as well as public archaeology have carried out the study in the summer of 2008. A “Mediated Window” was designed for the occasion, enabling visitors to remotely experience presence and interact between two locations, thus creating an architectural, mediated extension of space. Preliminary results confirm that presence in mediated spaces is to a high degree dependent on eye contact, can be achieved inexpensively but that many different design variables and illusory techniques borrowed from film, architecture and theatre must be addressed in designing presence. The paper argues that such new design contexts require combined skills in architectural design, user interaction and media technology. Results also show that large numbers of visitors, but also new categories of visitors, can be reached when mediated communication is applied to cultural heritage contexts, in combination with public learning activities outside museum buildings.