Nazi Germany called itself Das Drittes Reich – The Third Reich. Thus declaring that it was a successor, a descendant and (in a way) reincarnation of the First Reich – the Holy Roman Empire. Consequently, to understand the Third Reich (Nazi Germany), we must discover and understand a few basic facts about the First Reich.
Although the Holy Roman Empire was founded by Charlemagne who was Belgian by birth and a French king before he became the Holy Roman Emperor (and was crowned Emperor in Rome), it was born in a very German (and still very Catholic) city of Paderborn.
In 799 AD then-Pope Leo III fled his enemies in Rome and reached Paderborn, where he met Charlemagne. It was probably the most important meeting in the history of Europe because the Pope and the King decided that Charlemagne would be crowned emperor the very next year.
Thus making Charlemagne the first recognized emperor to rule from Western Europe since the fall of the Western Roman Empire three centuries earlier. Which made perfect sense because Charlemagne united (again for the first time since the fall of the previous Roman Empire) much of western and central Europe into one state (loosely coupled, but still a state).
The state that existed for one thousand years (this is where Nazi dreams of a thousand-year Reich came from).
However, only a hundred years after it was founded, the Holy Roman Empire ceased to exist for all practical purposes as the title of the Emperor had been contested by the rulers of Italy in a series of civil wars until the death of the last Italian claimant, Berengar I.
The Empire was re-established only in 962 AD, when the German king Otto I (Otto the Great) was crowned emperor, fashioning himself as the successor of Charlemagne and beginning a continuous existence of the empire for over eight centuries.
Consequently, although Holy Roman Empire was founded by the French king, for all practical purposes it was a German empire, the German state and the German Reich (most historians even consider the coronation of Otto I the actual beginning of an empire).
There is a general consensus among the medieval historians that the Holy Roman Empire was the cradle, the core, the foundation of the European (and Western) civilization as we know it. Hence, the Nazi claims that Germans were, indeed, the founders of the Western civilization were actually quite solid. Especially given the fact that the Imperial Parliament was seated in Regensburg and its Supreme Court – in Wetzlar (both very much German cities).
The Holy Roman Empire was essentially a confederation – a decentralized, limited elective monarchy composed of literally hundreds of different states. The power of the emperor was limited, and while the various princes, lords, bishops, and cities of the empire were vassals who owed the emperor their allegiance, they also possessed an extent of privileges that gave them de facto independence within their territories.
It appears that initially (prior to the realities of the World War II kicking in) Adolf Hitler and the Nazis had a similar vision of Europe as a confederation of semi-independent states led and ruled by the Nazi Germany.
Which (ironically) meant that they viewed Berlin as the Third Rome (albeit in secular, not religious way). They never used this term, of course (in order not to offend their Italian allies) but de-facto it was exactly that.
However, Nazi concept of the Third Rome was fundamentally different from the Russian (and the Soviet) one. Nazi vision was limited to Europe while the Soviets intended to conquer the entire world and Hitler did not strive to impose the Nazi ideology on its allies/partners (and in most cases not even on the occupied European nations).
The Bolsheviks were committed to “sovietization” of the occupied territories (i.e. to imposing the Bolshevik ideology on them) and to reengineering of these nations according to the fundamental principles of their ideology.
There was another interesting parallel between the First Reich and the Third Reich. In 955 AD, Otto the Great defeated the pagan Magyars at the Battle of Lechfeld, thus ending the Hungarian invasions of Western Europe. This victory earned Otto a reputation as a savior of Christian civilization.
Adolf Hitler intended to accomplish something very similar – to defeat the Bolsheviks (the Bolshevist Soviet Union) in a brief existential war (“blitzkrieg”), eliminate the existential threat of the Soviet invasion of Europe and earn a reputation as a savior of the Western civilization.
Another major accomplishment of Otto the Great were his successful wars against the East European Slavs. He defeated the Slavic tribes, broke up the Slavic federation and extended his control into Eastern Europe through military colonization and the establishment of Catholic churches. And that’s precisely what Adolf Hitler intended to do (minus establishment of churches, of course)
Another obvious parallel was in religious matters. Otto the Great transformed the Roman Catholic Church (at the time the only Christian church) in Germany to strengthen royal authority and subjected its clergy to his personal control.
Adolf Hitler intended to do the same thing (and on many issues actually did) with the Catholic, Lutheran and other Christian denominations in Germany and in German-controlled territories.
In short, Holy Roman Empire was a role model (a bit distant, but still a role model) and its German founder – Otto the Great – became a very personal role model for Adolf Hitler.