How did cathedrals increase business and trade in towns and cities

By the tenth century, many of these Roman cities had been abandoned, or had been reduced to fortresses, cathedrals, or monasteries with a nearby village, often enclosed by part of the old Roman wall. Nevertheless, they were still centers of population and generated a certain amount of traffic. Some village artisans moved to these centers, increasing their population and importance. The long-distance traders often found these locations convenient for breaking their journey, selling some of their goods, dividing cargo, or even trading with merchants arriving from distant parts. They often established residences and warehouses (called "factories") in the villages adjacent to the main administrative centers and took the lead in restoring and extending the old Roman walls to complete the defenses of an essentially new manufacturing and commercial center.

The presence of a population of artisans and merchants attracted a number of other specialists such as physicians, apothecaries, teachers, parchment-makers, scribes, lawyers, cobblers, furriers, butchers, bakers, cooks, prostitutes, barbers, tailors, and all of the other tradesmen necessary to support an urban population. Some of these centers developed some specialty of local manufacture.

either b) they were often feared and despised by other native cultures. or

c) their obsession allowed them to coexist with many other native cultures because of their peaceful nature.