The Church of St. Peter and St. Paul is the co-cathedral of the Roman Catholic Archdiocese of Đakovo-Osijek. A co-cathedral is a cathedral church which shares the function of being a bishop’s seat, or cathedral, with another cathedral, often in another city. http://croatia4me.com/en/travel-directory/co-cathedral-of-sts-peter-and-paul-in-osijek/