The church, a Romanesque basilika, consecrated in 1129, is in the form of a cross. The nave and the side-aisles are separated by six square columns, between which are rounded arcade arches. The half-pillars on the front of every second column are reminiscent of Saxon architecture. The measurements of the crossing, 8,22 x 8,22 metres, are the basic dimensions for the rest of the church. The round arch at the end of the nave echoes the double transversal arch resting on half-pillars with capitals above the entrance to the chancel. The green Anröchter dolomite of the arcades and the half-pillars form a contrast to the pale yellow of the Baumberger limestone of the main building.
Spanning the chancel, the crossing and the transept are groin vaults, which were taken over from the previous building of 1085. The roof of the nave was originally an open timber structure, which in 1498 Abbess Maria von Tecklenburg replaced with late gothic cross-ribbed vaults.