There were cities deemed imperial cities (I.C.) by certain emperors. They are shown in red in the map. Heilbronn is one and it is highlighted by a white circle. The large lavender area is the Duchy of Wurttemberg.
A duke or duchess would have influence over a duchy as would a bishop over a bishopric (see medium purple areas), a lord over a lordship (see yellow areas), an abbot or abbess over an abbey, and a prior over a priory.
The areas in green were ruled by secular princes of the Holy Roman Empire known as counts. Such a leader was called Count Palatine.
The darker purple areas were "teutonic order" (T.O.) lands - where a vassal was granted use of the land by his lord because of his fealty and support.
Here is Germany in 1990. The red dot is Munich. The bluish-green dot is Heilbronn.
