St. John's Church is a three-aisled basilica in neo-Romanesque style. It has a transept, a west tower and two east towers. The length of the church is 67 meters, including the wall and stairs 75 meters, the width 44 meters and the clear height of the central nave 20.5 meters. The two east towers each measure 41 meters, the west tower (with cross and rooster) 83 meters.
The church has a rich treasure trove of works of art and art objects. Some of the works of art, such as a 16th-century host, monstrances and chasubles from the Renaissance period, are on display in the Diocesan Museum in Paderborn.
