The small cathedral church from the time of the relocation of the bishop's seat no longer met the requirements of an important cathedral and trading town like Naumburg, which is why plans for major structural changes matured in the second half of the 12th century. The starting point was very probably the installation of the crypt under the east choir of the church. At first, the new construction of the eastern parts of the cathedral seemed to be based on the dimensions of its predecessor. But only a few years later, at the turn of the 12th to the 13th century, the decision must have been made in favour of a floor plan with a significantly enlarged longitudinal axis. The components that had already been created were tried to be integrated into the new concept as pleasingly as possible. Nevertheless, the plan change can still be seen today in the striking extension of the crypt and in the system of the eastern nave pillars.