In one embodiment, a computing device accesses a social graph comprising nodes and edges connecting the nodes. Each of the edges between two of the nodes represents a single degree of separation between them. The nodes include user nodes corresponding to users of an online social network, and concept nodes corresponding to places. A particular place corresponds to a particular concept node, and corresponds to an associated location and a perimeter. A number of check-ins are received, each check-in being associated with the particular place and having a geographic location. Each check-in corresponds to an edge of the social graph between a user node and the particular concept node. Based on the received check-ins the computing device determines whether to update the associated location and the perimeter.