Bonn had lots of interesting architecture, if you're into that sort of thing. There was also a house associated with some dead musical guy (it's been almost a year, memory, what's that? let me google...) named... Beethoven. You've probably heard of him. There's also an old town hall called Rathaus, I think, which is pretty photogenic. Bonn was apparently one of the first places they realized politicians are rats. The Markt (market) square is neat, lots of old buildings around it, and they do have markets in it. There's a bit of medieval castle wall a block or two from the Markt, including a gateway with a nice sturdy-looking portcullis gate thingy, which today guards access to a Döner Kebab shop! There's a cathedral kind of thingy called Bonn Minster with nice pointy steeples, and over near the Beethoven house there's Namen-Jesu-Kirche, another old church... I forget if they were working on the facade last spring.

Oh oh oh. If you go around late April or May, try to be there for the "Fire on the Rhine" fireworks display over the river. I think last year it was right around early May, like the 5th, give or take a couple days.