The Saint-Marc quarter, east of Saint-Maclou and centred on its weekly Sunday market, is the most lived-in part of central Rouen — less polished than the streets around the cathedral, more interesting at street level. Independent bookshops, small wine bars, the Sunday flea market on the Place Saint-Marc, and a steady undertow of students and artists give it more bite than the rest of the old town.
If you have time for a second walk after the cathedral and the main sights, this is the direction to take. Stop at the square for a coffee around 11am on Sunday, when the market is at its peak.