The Peace of Augsburg is the settlement between the Holy Roman Emperor and all his princes and nobility that established that the religion of a locality in Imperial Germany will be the same as that of its ruler. The only two religions allowed were what we today call Lutheranism and Roman Catholicism. At the Peace every German state and principality had its religion determined.
Many people may wonder what the 460 year old Religious Peace of Augsburg has to do with a modern European state. I did too until recently when I started to think about it. Let me lay out my train of thought. It all started with the German holiday that is celebrated today. That holiday is Maria Himmelfahrt or the Assumption of Mary in English. That is a Roman Catholic holiday and what it has to do with the Peace of Augsburg is the following. After the peace, each city, town, and region in Germany was allotted to a different confession. Those distinctions have held down to the present day whether they have any relation to present reality or not.
The reason it applies to modern Germany is because there are specific holidays on the German calendar that are only observed by Catholic communities and vice-versa. Maria Himmelfahrt, being a Catholic holiday brought this up last week when we were talking some friends of ours. The town I live in, Kemnath, is Catholic and even today overwhelmingly so, something like 95%. It also celebrates Maria Himmelfahrt and the stroes are closed ad everything else that applies on a typical German holiday. A friend of ours lives in Neustadt am Kulm, about 3 miles from us, it is a Lutheran town and Maria Himmelfahrt is not observed there so they have to work. I remarked when we were talking about it that the distinctions were a medieval remnant and it was good for a laugh.
However, if you really think about it, things like this should bring home how the past is not really dead even though many people like to think it is.