The double sided cross altar and the Lettnerwand, taller than a human, divided the monks`choir pews in the eastern part from the lay brothers’ seating in the western part. The altar was probably created under the supervision of a Bohemian or south German master builder, with the help of north German master Bertram von Minden. The time of creation is dated 1360-1370. It is the most monumental of its kind in Europe. For the dedication of the church in 1368 the greater part of it was probably finished. 