A navigation method and system determines a more accurate position of a street address number with use of building footprint information or latitude/longitude information of POI (point of interest), thereby accurately defining a position of a destination. When a user specifies a street address number as his destination, the navigation system retrieves the street segment that should include the location of the specified address number therein. The navigation system also checks the map data as to whether there is any building footprint data or POI position data associated with the street segment. The navigation system selects absolute locations on the street segment based on the building footprint data or the POI position data and determines the location of the specified address number by interpolating between two absolute locations.