The palette
Water surrounds the old town on three sides, so it colours the poster as much as the land does: a deep ink makes the point stand out sharply, a soft one lets the marshes and the streets share the attention. Green has a great deal to do on this map, because the marshes are in the data and follow every far shore in ragged bands. Choose a green that stays clearly apart from the water, or the shoreline will blur where the two meet. Inside the old town, everything is line work.