Trade and the Recycling of Stones in Medieval Cologne

The vita of Archbishop Heribert of Cologne reports that after the collapse of the monastery church in Cologne-Deutz in 1000 AD, the Archbishop “hired experienced architects from abroad […] and entrusted them with the task of the entire construction site”. This is among the earliest evidence of a professional building organisation in Cologne. Numerous publications have appeared on the organisation of the Cologne building sites from the eleventh to the fifteenth century; these have discussed the several crafts, the construction process, and the building materials, among other topics. However, the historical sources are largely absent for the centuries before. Many building remains (especially churches) from the early Middle Ages have been excavated in Cologne. It has been shown that Roman buildings were recycled during this period and well into the High Middle Ages. This chapter compiles the most important findings of the Merovingian and Carolingian periods from about 100 years of city archaeology in Cologne. The focus is on the building materials and the construction techniques of the masonry as well as the extensive recycling of the Roman city.