Hildesheim , one of the oldest cities in Northern Germany , became the seat of the Bishopric of Hildesheim in 815 and may have been founded when the bishop moved from Elze to the Innerste ford , where it was an important market on the Hellweg trade route .
The city may have been founded when the bishop moved from Elze to the Innerste ford , where it was an important market on the Hellweg trade route .