The existing church is a three-aisled basilica. It was partly built on the old foundation walls in the 11th c. after the old St. Peter's Church was demolished. From its inception, the interior was decorated with rich wall paintings. The painting in the apse,still visible today, dates back to 1104-1105 and is divided into three zones. The Majestas Domini is depicted in the uppermost zone accompanied by the four evangelist symbols. Peter and Paul worship on the right and left. The twelve apostles occupy the middle zone with the prophets below. Around 1750, the church was extensively redesigned in the Rococo style.
