View over Cathedral Island of Wroclaw. Cathedral Island is the oldest part of the city of Wrocław. Nicolas Copernicus was a resident of Cathedral Island from 1503-1538. The Cathedral of St. John the Baptist is the seat of the Roman Catholic Archdiocese of Wrocław and a landmark of the city. The cathedral, located in the heart of Cathedral Island district, is a Gothic church with Neo-Gothic additions. The current standing cathedral is the fourth church to have been built on the site and was substantially rebuilt after being about 70% destroyed in the siege of Breslau at the end of World War II.