Between 1122 and 1200, the city walls were erected, pierced by three gates (Scotch Gate, Irish Gate and English Gate) and defended by six towers on the vulnerable north-eastern perimeter. Outside the walls, a deep ditch provided additional defence. Town Dyke car park is built over (and named after) this ditch.
In 1158, Carlisle gained a Royal Charter to hold a weekly market and a Great Fair in late August. Vegetables were sold in the Greenmarket, corn in English Street and meat from the shambles (outside House of Fraser). Wool, cloth and leather were important commodities and regularly exported to Scotland, Ireland and northern Europe. To protect trade, guilds were established for weavers, tailors, tanners, glovers, shoemakers (cordwainers), smiths, butchers and merchants, who met in the medieval half-timbered Guildhall.