…and if you are in Europe anyways, you can also visit Giessen’s Mathematikum, which offers experimental experience of mathematical phenomenons for all senses. Furthermore, you could visit Göttingen - the collection of mathematical models is nice, but of course the real highlight is to try to trace the marks left on maths and physics by means of tracking down commemorative plaques, street signs, and graves of great mathematicians throughout the city.
Ideally, you start in Göttingen (maybe pay a short visit to Hannover for Leibniz), then go to Giessen, and then to Bonn. You might as well also visit Paderborn, if you are at it. ¯_(ツ)_/¯
