Location detection remains a challenge in busy urban surroundings. The high rise canyons prove a difficult to overcome obstacle for GPS. The aim of our study was to investigate whether existing wireless LAN infra-structure can be used for positioning in an inner city environment. While some success of indoors WLAN positioning has been reported under laboratory conditions in the past, these approaches have relied heavily on strategic placement of the wireless base stations that act as beacons for such systems. Moreover, the most accurate approaches model the propagation of the radio frequency signal and thus rely on an extremely stable environment that can only be constructed under controlled conditions. We investigated whether the wireless LAN signals in a quite dynamic inner city environment could be used for positioning purposes within the existing infrastructure and without the installation of a dedicated set of wireless access points for that purpose.