St. John the Baptist and St. John the Evangelist. ul. Żaglowa 16. One of the largest monumental churches in Poland. A treasury of many priceless works of art. Construction took over 200 years. Place of the baptism of Nicolaus Copernicus. It has hosted almost all polish kings in its walls, the heart of Jan Olbracht is also here. The Tuba Dei, the largest medieval bell in Central Europe, has been hanging here since 1500.