The Herbarium is a small garden set into the slope below the ramparts, planted with several hundred species of medicinal, culinary, and dye plants used in northern France since the Middle Ages. The garden is organised into beds by theme — kitchen herbs, fragrant plants, plants used in textile dyeing, plants traditionally believed to have healing properties — each labelled with name and use.
It takes maybe half an hour to walk through, and it pairs well with a wander along the rampart path immediately above. The setting itself, with the chalk wall on one side and views over the bay on the other, is half the appeal. Entry is free; the garden is open from spring to autumn.