Why were granaries and storehouses built along the Vistula River?

Granaries and storehouses were built along the Vistula River primarily to support its role as a vital trade route.1

Beginning in the 10th century, the river became a major artery for transporting essential goods, including salt, timber, building stone, and grain. The construction of these facilities, which intensified during the 14th century, allowed for the storage and management of these commodities as they were moved along the waterway. This infrastructure was particularly significant during the period from the 15th to the 18th century, when the Vistula served as a primary trade route for central Europe.1