Titles of European royal heirs

Many past and present European monarchies have reserved titles used just by the heir apparent to the throne. The famous example of this is Charles, Prince of Wales, former heir to the British throne. Many heir have had “crown prince” as their title.
Territories prior to unification.
German states.
Prior to the unification of Germany, the area was made up of dozens of small principalities such as Duchies and Grand Duchies and most of them used the titles of Hereditary Grand Duke or Hereditary Prince [followed by name of state] such as:
Italian states.
Prior to the unification of Italy, the area was made up of independent Kingdoms, Duchies and Grand Duchies.