New research reshapes our understanding of Danish architectural heritage

For more than a century, building archaeologists have believed that the art of brick building in Denmark was imported directly from Lombardy in northern Italy in the mid-12th century. But a new scientific study reveals that the story is far more complex.

“Our analyses show that there is no evidence for a direct transfer of brickmaking technology from Italy to Denmark in the 1100s,” says professor emeritus Kaare Lund Rasmussen from the Department of Physics, Chemistry and Pharmacy, University of Southern Denmark. He specializes in archaeometric analyses—chemical investigations of cultural heritage objects.

Instead, the evidence points to knowledge spreading through the Cistercian monastic network, likely making a stop in Germany before reaching Denmark.

The study was conducted in collaboration with colleagues from the National Museum of Denmark, Over Byen Architects, Cranfield University in England, the Institute of Heritage Science and the University of Pisa in Italy, as well as Universidad Nacional de Catamarca in Argentina. It was published in npj Heritage Science and supported by the AP Møller Foundation and the Augustinus Foundation.

When King Valdemar the Great and Bishop Absalon built the Danish monastery churches in Ringsted and Sorø in the 1160s, it marked a turning point in Danish building culture. For the first time, large red brick churches rose in a country where buildings had previously been constructed in wood or natural stone.

Bricks quickly became a symbol of prestige and power. King Valdemar even expanded the Danevirke fortification with a kilometer-long brick wall—one of the largest construction projects of medieval Denmark.

305 Brick Samples Under the Microscope

The research team analyzed 305 brick samples from two Danish churches in Ringsted and Sorø and two Italian churches: Chiaravalle Milanese and Abbadia Cerreto in Lombardy, south of Milan. Using advanced methods such as thermoluminescence dating, X-ray diffraction, and color measurements, they determined age, raw materials, and production techniques.

The results show no trace of Italian craftsmanship in the Danish bricks—no “fingerprints” of Lombard builders.

“If Italian craftsmen had been involved, we would expect to see certain technical details—specific mortar mixtures, characteristic firing techniques, or decorative elements—replicated in Denmark. But the Danish churches lack these features,” explains Kaare Lund Rasmussen. As one example, he notes that mortar joints in Italian churches are only a few millimeters wide, while in Denmark they can be several centimeters.

According to study co-author Thomas Bertelsen, a building archaeologist and restoration expert at Over Byen Architects in Copenhagen, cultural historians have traditionally dated the Italian churches on the Po Valley to the 12th century, making them nearly contemporary with the Danish ones.

“That was one of the reasons people thought Denmark might have received brick technology directly from Lombardy,” he says.

But chemical analyses revealed that Chiaravalle is significantly younger than previously assumed, while Cerreto is older. This means Cerreto’s bricks were fired decades—perhaps even a century—before the Danish churches were built.

Chiaravalle, on the other hand, turned out to be about 75 years younger than the Danish churches, ruling out its builders as a source of Danish brickmaking knowledge.

“It simply cannot have been the same master builders and craftsmen who constructed both Cerreto and the Danish churches. They would have been too old—or even dead—by the time work began in Denmark,” says Kaare Lund Rasmussen.

Thomas Bertelsen adds that the craftsmanship differs so greatly between the Danish and Italian churches that it seems highly unlikely the same people built them. In Italy, surface treatments were more refined, joints narrower, and stones carefully shaped for use in columns.

“That level of care is not recognizable in Denmark. These are entirely different builders. We have demonstrated that it was not North Italians who came to Denmark to construct the churches,” Bertelsen emphasizes.

Instead of a direct link between Lombardy and Denmark, the researchers suggest an indirect spread of knowledge. The Cistercian order, renowned for its international monastic network, likely played a central role.

At the same time, brick construction was developing in northern Germany around Lübeck in the late 12th century.

“It’s a good example of how technology and architecture in the Middle Ages could spread gradually through networks of monks, craftsmen, and trade routes—not just through kings and wars,” explains Kaare Lund Rasmussen.