A system for providing location relevant information to users of a plurality of mobile devices within a multi-storey building, the system comprising: a plurality of transmitters located in different locations across multiple floors of the building, each transmitter for transmitting a signal for identifying the location of its associated transmitter; and software for running on the plurality of mobile devices, the software being operable on each mobile device for: identifying signals received substantially concurrently from two or more of the plurality of transmitters; and displaying on the mobile device location relevant information, characterised in that: the signals transmitted at least by transmitters located on the same floor share at least one common transmission parameter and a common floor identification artifact for identifying the floor on which the respective transmitters are located, and wherein the software is further operable to determine the closest transmitter on the same floor as the mobile device based at least in part on the at least one common transmission parameter and by identifying the floor on which the mobile device is located by selecting the floor associated with the highest number of detected common floor identification artifacts from the signals received from the two or more of the plurality of transmitters, and the displayed location relevant information is associated with the location of the determined closest transmitter on the same floor. a plurality of transmitters located in different locations across multiple floors of the building, each transmitter for transmitting a signal for identifying the location of its associated transmitter; and software for running on the plurality of mobile devices, the software being operable on each mobile device for: identifying signals received substantially concurrently from two or more of the plurality of transmitters; and displaying on the mobile device location relevant information, characterised in that: the signals transmitted at least by transmitters located on the same floor share at least one common transmission parameter and a common floor identification artifact for identifying the floor on which the respective transmitters are located, and wherein the software is further operable to determine the closest transmitter on the same floor as the mobile device based at least in part on the at least one common transmission parameter and by identifying the floor on which the mobile device is located by selecting the floor associated with the highest number of detected common floor identification artifacts from the signals received from the two or more of the plurality of transmitters, and the displayed location relevant information is associated with the location of the determined closest transmitter on the same floor. identifying signals received substantially concurrently from two or more of the plurality of transmitters; and displaying on the mobile device location relevant information, the signals transmitted at least by transmitters located on the same floor share at least one common transmission parameter and a common floor identification artifact for identifying the floor on which the respective transmitters are located, and wherein the software is further operable to determine the closest transmitter on the same floor as the mobile device based at least in part on the at least one common transmission parameter and by identifying the floor on which the mobile device is located by selecting the floor associated with the highest number of detected common floor identification artifacts from the signals received from the two or more of the plurality of transmitters, and the displayed location relevant information is associated with the location of the determined closest transmitter on the same floor.