Museums attract increasing numbers of online visitors along with their conventional physical visitors. This paper presents a study of a mixed reality system that allows web, virtual reality and physical visitors to share a museum visit together in real time. Our system allows visitors to share their location and orientation, communicate over a voice channel, and jointly navigate around a shared information space. Results from a study of 34 users of the system show that visiting with the system was highly interactive and retained many of the attractions of a traditional shared exhibition visit. Specifically, users could navigate together, collaborate around objects and discuss exhibits. These findings have implications for non-museum settings, in particular how location awareness is a powerful resource for collaboration, and how 'hybrid objects' can support collaboration at-a-distance.