Aachen Cathedral Springs are a Fairy Tale
There never were cathedral springs. This mistaken assumption, based on the finds of Roman baths during the construction of the Hungarian Chapel in 1755, has been dropped. As Prof. Thomas R. Rüde from the Department of Hydrogeology outlines in a recently published first volume of Aachen city history, drilling during restoration work on the cathedral in the last two years can clearly prove that the limestone layers containing the thermal water lay over 7 meters under the floor of the cathedral and more than 4 meters under the floor level of the Romans.
"According to these findings, it is impossible that there were ever thermal springs under the Hungarian chapel that Romans could have reached," writes Lydia Seiffert in her Bachelor thesis "Oberflächennahe Gesteine under dem Dom zu Aachen und die Frage der thermalen Domquelle." (Stones near to the surface under the Aachen cathedral and the question of the cathedral thermal springs)
Limestone Deposits under the Aachen Cathedral
During construction of the Hungarian Chapel in 1755, remains of Roman walls were discovered underground. The function of the remains was debated for a long time, until 1952/53, when Hans Christ interpreted the remains as a Roman spring tap that provided neighboring bath houses with water.
Geological investigations could only first be made in 2007 to 2009 during the archaeological digs under the floor panel of the octagon and thus, the thermal facilities underneath the cathedral. A total of thirteen holes were drilled around the octagon. As a result, previous research could be confirmed, namely that there are layers of limestone everywhere underneath the cathedral, which until then were only known to be under the choir loft. As Lydia Seiffert explains: "Only there can you find the limestone layer which provides several other Aachen locations with thermal water."
The limestone under the octagon however is covered by other deposits – as a result the thermal water remained deep in the ground. It was proven that there was spring water under the octagon at a depth of 7.23 meters underneath the top of the floor, and thus 4.80 meters below the floor level of the Romans. "It lies much too deep under the floor to have been used by the Romans," concludes Lydia Seiffert.
According to the most recent archaeological interpretations the Roman findings under the Hungarian Chapel are part of a hypocaust – a type of floor heating, with which a relaxation room such as spa complex can be heated. Due to the existence of ducts that were found by archaeologists in the late 19th century, City Archaeologist Andreas Schaub and his team assume that the thermal bath was fed by the Quirinus spring, which is not as deep underground.
"The archaeological and geological results are in accordance with one another on this point," summarizes Professor Rüde. "Unfortunately, there never were cathedral springs."