System and method are directed towards determining an approximate location of a cell tower (CT), using at least implicit location information obtained from a plurality of mobile devices obtained while each mobile device user employs a location based application. Also obtained are CT identifiers associated with a cell tower each mobile device is currently employing. When a sufficient number of mobile devices provide implicit location information for a given CT identifier, an approximate location may be determined. Subsequently, when a mobile device provides a CT identifier for which an approximate location has been determined, the approximate location information may be used to assist the user of the mobile device. For example, the user might access a location based application and automatically have an approximate location of the user's mobile device be provided to the application transparent to the user.