Commerce is a necessary part of any settlement that has the feel of a town. It does not require monumental buildings for it to happen. Many a thriving country town has flourished with traders bringing their goods to sell from the back of a cart or a tray set out on the ground.
The activity is important not only for the town but also for the countryside, where some of the money goes, helping to sustain the population as it grows the next crop, scrapes salt off rocks by the sea or lands the next catch of fish.
Commerce can be very well developed without leaving any trace. In such ...