If you ask about the age of city, do you expect to be told it founding date or its age?
If you said founding date, you will be as confused as I was by:
You can see the map in its full confusion.
The age of Aubsburg is indeed 2013, but 15 BCE (on orders of the Emperor Augustus) established the same fact with less effort on the part of the reader.
Making users work for information is always a poor communication strategy. Always.