More than a thousand years ago, Poznań was one of the main centres of the emerging Polish state. On its Ostrów Tumski (Cathedral Island), a palatium – the seat of the Piast duke – was built at that time, among other things, as well as the first Polish cathedral, which, after numerous rebuildings, still stands today and serves the faithful as the Archcathedral Basilica of the Holy Apostles Peter and Paul.The basilica is a beautiful Gothic building. Its interior holds a wealth of valuable treasures, including the famous bronze tomb slabs from the Vischer workshop, a medieval high altar in the form of a polyptych, and bishops' tombs and epitaphs. It is worth remembering that the cathedral is the burial place of kings and princes of the Piast dynasty. The Golden Chapel, with the sarcophagus of Mieszko I and Bolesław the Brave, makes a great impression.The audio guide also takes you to the church's underground, where you can see, among other things, the probable site of Mieszko I's baptism and a crypt with the coffins of the bishops of Poznań.