A system for capturing and delivering location-based information and services captures wireless landmark information sent by mobile devices to build a map of locations based on the relationship between wireless landmarks that are visible to the mobile device at the same time. A wireless landmark may be a cellular telephone base site or local network (WiFi/Bluetooth) access point. The mobile device may capture a location signature using identifiers for all wireless local area networks in range as well as one or more cellular telephone transmitters. A location service resolves the location signature into a relative location that an application service may use to record incoming information or to send location-specific information such as traveler comments, reviews, or advertisements. The distance between two mobile devices may be calculated using weighted edge values, representing a number of ‘hops’ between location signatures.