System and methods for locating a mobile computing unit are described. In some cases the systems and/or methods determine, at a mobile computing unit, the mobile computing unit's absolute coordinates using received radio frequency ("RF") signals from RF beacons using known coordinates for the RF beacons and an environmental profile. In some other cases, the systems and/or methods determine a location within a building of a mobile computing by receiving RF signals from a plurality of RF beacons having known locations and using a previously established radio map of the building to establish the location within the building of the mobile computing unit.