In the year 1000, the Kraków diocese was established followed by the construction of a Cathedral – the seat of the bishop. However, as a result of an ongoing conflict with the Holy Roman Empire, construction did not begin until the signing of the Peace of Bautzen, in 1018. Only minor fragments remain of the original cathedral (which is sometimes called ‘Chrobrowska’ after Bolesław I the Brave) and despite extensive archaeological research, it has proved impossible to reconstruct its exterior. Until the 1980s, relicts of St Gereon's Church were identified with the first cathedral but this theory, advanced by Adolf Szyszko-Bohusz, has been disproved by more recent research. There are also inconsistencies in the dating of the destruction of the original cathedral. Some sources place this at the time of the invasion of Bretislaus I of Bohemia in the 1040s, while others date the destruction to a fire in the 1080s.