The Niederburg is the oldest part of Konstanz — a dense tangle of medieval lanes between the cathedral and the Rhine outflow — and it holds the greatest concentration of eating options in the city. The streets are narrow enough that competing restaurants face each other across the cobbles, and in summer the whole area fills with outdoor tables.
The range is wide: fish restaurants serving the day's Felchen catch, Turkish and Italian places popular with students, wine bars offering local Baden Pinot Noir by the glass. It's the right area to walk through before deciding — menus are posted at the door and the atmosphere is clear from the street.