During renovations on the Evangelical Church of Saint John in Mainz, Germany, workers have discovered remains that make it the second oldest church in Germany. They were installing a heating system under the nave when they found remains of a previous floor built in the ninth century about three meters (10 feet) below the current floor level. This earlier floor dates to the construction of the church by Archbishop on Mainz Hatto I.
Archaeologists excavated further, exploring the basement as well where they found even older structures from the 7th and 8th centuries. The remains are impressive in dimension. Walls reach as high as 10 meters (33 feet). Hatto I consecrated what was then St. Salvator, the cathedral and seat of the Bishop of Mainz, in 911, but it seems the remains of an older church were incorporated into the new construction. Hatto’s cathedral walls were built against the older ones instead of on top of it, thus allowing a very rare survival of substantial Carolingian structures.
“This is a big surprise,” he said.
The Rhineland-Palatinate state curator Joachim Glatz said: “This is the only surviving Carolingian cathedral in Germany.”
Usually a bishop would build a cathedral in the Middle Ages at the exact location of the previous building, getting rid of the older church. But in Mainz the 1,000-year-old “Old Cathedral” was incorporated into the Carolingian one.
The surviving structure points to a church with a very different configuration from Hatto’s cathedral. According to Professor Untermann, the church had a small nave with a transept on the west side and double altars, one in the west and one in the east, an unusual feature.
Archaeologists also discovered two graves in the basement. One was a sarcophagus without a lid, the other a stone walled cyst. Both held skeletal remains. They have yet to be dated, but they area likely to be older than the 7th-8th century walls. There are no inscriptions or grave goods pointing to the identity of the deceased, but they were probably people of importance, secular leaders or high clerics. The style of the sarcophagus indicates it was made in the early Middle Ages. That doesn’t testify to the age of the burial, however, because it could have been reused multiple times since it was first crafted.
If the dating of the walls and graves is confirmed as Carolingian or older, that will make St. John’s the second oldest church in Germany. Only the High Cathedral of Saint Peter in Trier can claim greater age, thanks to its central chapel which was built at the direction of Saint Helena, emperor Constantine’s mother, in the 4th century.
Excavations are ongoing. At some point the church is going to back to full service — right now its parishioners are using the city hall and other local churches — but St. John’s leaders are very excited about the finds and once the digging is done, want to find a way to integrate the archaeological remains with the current church and make them visible to the public. They are also beginning the process of having the church declared a national heritage site.