Trier turned out to be a strange town. It dates back to Roman times and got damaged in various wars. So, it got a strange amalgamation of different architectural styles. The cathedral in the middle of the city summarizes it well: it has a roman foundation, a romanesque ground floor, a gothic roof, baroque decoration in side, and rather-modern stained glass windows. None of those layers represent the best of the respective styles, but it sure is an interesting combination.