Students want to find out more about the land and people. Since German castles can be an attractive travel destination, your students are going to love this topic. Of course, you should work with pictures and videos if possible. You can explain to them that Germany was divided in numerous principalities for a long time which is why there are so many castles in Germany.
german castles – a text in English.
You can also work with videos like this one:
A map which shows that Germany was divided in about 300 principalities at some point (14th/15th century) which is why there are so many castles in Germany: