Augmented reality is a powerful user interface technology that augments the user’s environment with computer generated entities In this venture we investigate building indoor location based applications for a mobile augmented reality system. Augmented reality is a natural interface to visualize special information such as position or direction of locations and objects for location based applications that process and present information based on the user’s position in the real world. To enable such applications we construct an indoor tracking system that covers a substantial part of a building. It is based on visual tracking of fiducial markers enhanced with an inertial sensor for fast rotational updates This is especially problematic for mobile augmented reality systems, which ideally require extremely precise position tracking for the user’s head, but which may not always be able to achieve the necessary level of accuracy. While it is possible to ignore variable positional accuracy in an augmented reality user interface, this can make for a confusing system; for example, when accuracy is low, virtual objects that are nominally registered with real ones may be too far off to be of use. Our system uses inferencing and path planning to guide users toward targets that they choose.