After dark, the Niederburg shifts from restaurants to bars. The lanes between the cathedral and the Rhine outflow hold a cluster of small bars where the clientele is mostly students and young locals. Places open late, stay open later, and the atmosphere is friendly without being rowdy.
The bars are small and the turnover between them is part of the evening — a drink in one place, then moving on. Local Baden wines and German lagers are both well represented. The area is compact enough that you can find the right place on foot without a plan.