The king Saint Stephen founded the diocese of Eger. We do not know the exact date, but we are positive that it existed in 1009 under the protection of the apostle Saint John and the evangelist John. The old center stood where the castle stands today, near Saint John Abbey. The oldest ecclesiastic building found there was built around the turn of the 10-11th centuries. It is probable that the third bishop of Eger, Buldus, who died when Saint Gellért did, was buried there.