Not been to Mannheim, but have been to Germany a couple of times and it’s a nice place. The people are very tidy. Report back and tell s if it’s worth a visit.
I like Germany. Been to Berlin, Munich, Hamburg, Hanover and Cuxhaven. Hanover was flattened (VW commercial vehicles were and are still built there) so lacks some character. I guess Mannheim may be like this.
Been twice with football when I was a lad playing for Cwm Albion Colts,seem remember the city being clean and a lot of historical buildings and in general a very nice place to visit, although I didn't care much about those things back then. We played games against SV Waldhof (I think that's how it's spelt), at their stadium which I think has been refurbished and is now called the Carl Benz Arena, Well worth a visit if you're close by, enjoy! 👍