Archaeologists in Mainz, Germany have discovered the second oldest church and the only surviving Carolingian cathedral in Germany. Within the walls of the city's Church of St John lie the remains of a 9th century structure whose walls "stretch from the basement to the roof."
“This is a big surprise," said Professor Matthias Untermann from the Institute of Art History in Heidelberg. According to experts, instead of tearing down the older structure, builders incorporated the new church into the older one. Only the city of Trier has an older church.