There is a one very important issue related to adoption of landmarks which is good to understand when utilizing landmarks in map services, visualization, navigation or defining locations: How the center point of a landmark (exact coordinates) is determined and presented in a single point, and what are the most appropriate selection criteria’s and principles to select this point.

If you compare available map services (Google Maps, Yahoo Maps, Google Earth, Bing Maps, etc.), you will realize that location of the landmarks and such are not identical at all. Everyone has their own version of where the center points of landmarks are located. Cities, towns and villages are more or less “somewhere there”, POI (Point of Interest) type of landmarks are usually close to, but not exactly where the "real position" is.

This is one of the core issues with landmarks – How to determine and place the center point of the single point which represents city, village or another man-made landmark? Should the selection be based on functional, geographical, administrative principles or just on one person's perception? In geography, mathematics and especially in cartography, this issue/problem have been analyzed extensively, but no straightforward and generally accepted solution has been presented... And never will.

Since the theories and principles never provide the correct and absolute answer, the correct answer depends on the primary use of landmark. In this case, all the criteria’s and principles can affect the location separately or all together with different degree. If we ignore all the mathematical models, scales and map projections, the center of the landmark can be set through four general principles:

Functional

On this basis, the landmark locates in the functional focal point of a city or a village, in the center of the area where the most traffic flows and commercial activities are concentrated. In the case of POI type of landmark, center point locates where people mostly move within the area of landmark, usually in main entrance of the building/premise/area.

Functional location of Juba and Juba Teaching Hospital

Geographical

On this basis, the center of a city or a village is placed into mathematical center of their geographical borderline polygon that determines the operational area (built up area). The center of POI type of landmark is also defined by the center of a polygon that usually is based on a building outline or something similar.

Geographical location of Juba and Juba Teaching Hospital

Administrative

On this basis, the location of the landmark is relatively easy as it is placed in the mathematical center of an administrative city/village limit polygon. This polygon may be the same as the geographical, but often it is not. In case of POI type of landmarks, center point is located according to mathematical center of a property or site, according to the compound boundary polygon.

Administrative location of Juba and Juba Teaching Hospital

Personal Perception

This is “the principle” that confuses and messes up all the other criteria and principles, but is the most important of them all. How can one person define where the center point of a city, village, or a single building should be? There are a lot of studies and tests about this: Approx 90% of the people place the center of the city within one kilometer radius from the functional center. For POI-type of landmark, they place center point as follows: 40% in the middle of the building, 40% in the main entrance and 10% elsewhere.

My location for Juba and Juba Teaching Hospital

So, where is the center of a landmark? If none of these four principles work directly for a particular landmark, it is useful to make an appropriate synthesis of these four. This kind of generalization usually works well and provides good and generally accepted answer.

However this is not a totally definitive response to the question where the center point of a landmark should be located, but it provides the basis for how the center point can be determined.