Imagine chisels biting into stone. These Historische Steinbrüche once echoed with the sounds of labor. We stand at a place that provided the very building blocks of Freiburg. The Historische Steinbrüche tell a story of craftsmanship and ingenuity.
The Freiburger Münster owes its existence to these quarries. The red sandstone that graces the cathedral came from here. Freiburg was fortunate to have several quarries nearby. This proximity made sandstone the primary building material for the Münster. Consider this: the Münster incorporates approximately 20,400 cubic meters of natural stone. This equates to a staggering 47,000 tons. These figures exclude foundations, vaults, roofs, and modern additions. The Historische Steinbrüche provided much of this material.
Early on, the Münster acquired stone from a quarry on Lorettoberg. This quarry was documented as “Unser Vrowen Steingruob” in 1332. However, recent studies suggest Lorettoberg supplied less stone than previously thought. Large quantities likely came from the Hornwald ridge near Emmendingen. The large yellow-red stone blocks used in the late Romanesque transept, the lower parts of the Hahnentürme, the Gothic nave, and much of the main tower probably originated there.
By 1324, the Münster factory utilized a new quarry in Tennenbach. This quarry was about four kilometers from the Hornwald. Cistercians had already constructed a monastery there around 1160. They used blocks from nearby quarries. The Münster quarry expanded and supplied stones until the 19th century. Even today, it is visible above the Aubächle valley. Tennenbach is situated in the southern Lahr-Emmendingen foothills. This area contains large deposits of building sandstone.
The high quality of Tennenbach sandstone led to the development of numerous quarries in this region. The distinctive Tennenbach conglomerate sandstone was used in the upper part of the Münster’s tower. It was also used in the Hahnentürme extensions and the choir.
Despite having its own quarries, the Münster building workshop also sourced materials from elsewhere. Fine-grained plate sandstone from Wöpplinsberg near Mundingen was used for the tracery of the choir chapels and parapets. Limestone from Pfaffenweiler was used for interior work and sculptures. In the 18th century, sandstone from the large quarries of Heimbach was likely used for the choir’s chapel pillar attachments.
Storms, wars, and weathering necessitated replacement materials. This was especially true after the Tennenbach quarry ceased producing usable stone around 1820. The Münster building workshop and the Münsterbauverein no longer owned quarries. Instead, they relied on purchasing suitable stone from other quarries. Since the late 19th century, sandstone has been sourced from beyond the Lahr-Emmendingen foothills. Quarries in Alsace, the Neckar, and the Main became suppliers. Even smaller quantities of sandstone from Saxony and Silesia were used.
Today, the Münster building workshop has returned to Tennenbach for replacement material. An old quarry near the former one has been reopened. Excavation uncovered iron wedges and chain parts. These tools from around 1920-1940 were used for detaching, dividing, and lifting stone blocks. Similar tools were used in the Middle Ages.
Initially, it was believed that red and yellow sandstone came from Lorettoberg. This was during the Romanesque construction phase of the Münster. However, large blocks for foundations and wall stones are not found there. Instead, thin-bedded fine sandstones are present. These were used in medieval cellars and the Münster’s attic. The large yellow and red sandstone blocks came from the Hornwald ridge near Sexau. Over half the wall stones for the Hochburg fortress are made of yellow sandstone. The same as the Romanesque part of the Münster.
The three finials displayed came from the main tower’s upper gallery. They illustrate the different stones used and the search for the best material. The left finial dates back to around 1310. It was likely carved from Tennenbach sandstone. The middle finial is an example made from Freudenstadt plate sandstone in the 1960s. This sandstone is not very resistant to weathering. It will be replaced during the next renovation of the main tower. The right finial will be installed. It is made of Neckartal hard sandstone.
The Tennenbach quarry was demonstrably owned by the Münster factory since 1324. It was expanded in the 14th century. In 1820, it was noted that the Münster quarry was completely exhausted. In 2012, iron wedges and parts of a chain were uncovered during excavation work. Though quarrying methods have evolved over the centuries, tools like wedges and chains were always essential for working stone.