The Verkehrsmuseum is one of Nuremberg's strongest museums, especially if railways interest you even a little. Its DB Museum collection traces German railway history through locomotives, models, carriages, and the social story of how trains changed travel.
It is also a useful indoor counterweight to the old town and Nazi-era sites. Give it proper time rather than treating it as a rainy-day fallback; the collection is broad enough to satisfy transport obsessives and still accessible for casual visitors.