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. During two weeks in the summer of 2008 the Stockholm Art and Industry Fair of 1897 was excavated as part of a collaborative process between archaeologists and the general public. A “Mediated Window” was designed which enabled visitors to remotely experience presence and to interact between the museum and the excavation site, thus creating an architectural, mediated extension of space. The case study confirmed that mutual gaze is important to the experience of presence and that a combination of architectural and technical design is required to fully support this experience. The mediated museum extension attracted large numbers of visitors, including new categories of visitors who were less likely to visit the museum. The study showed that a mediated extension, in combination with outdoor public learning activities and participation, can evoke an interest in modern cultural heritage and promote public dialogue in such contexts.