Someone once said that the odd thing about the Holy Roman Empire is that it was not holy, Roman or an empire. This mostly Germanic and North Italian territory was organised under Otto I, who had been crowned by the Pope (holy) in the year 962. In what we call The Middle Ages the Emperor tried to represent an attempt to maintain ancient Roman traditions of European unity blessed by a purely Christian conept of authority ordained by God. Naturally this was resented and there was constant friction with several Popes, which led at the end of the 15th century to an ‘Empire’ which was little more than a legal term for an instituted trusteeship of the German or Teutonic States.
From 1273/4 the Empire was dominated by the Habsburg family, who were intent on territorial expansion, and considered many lands outside their boundaries as part of the Empire, nevertheless.
Napoleon Bonaparte is responsible for the liquidation of the Holy Roman Empire because he wished to establish his own, French-dominated Empire, and it was formally abolished in June 1806. The last Emperor, Francis II, reigned thereafter as Emperor of Austria.