The origine of this church is romanesque. It is one of the chruches that were built under the famous Prins-Bishop Notger between 980 and 988. He built this chruch are thanks to God for him winning from the horrible count of Chèvremont.
The western tower in sandstone, with the 2 staircase turrets are remainders from the original Romanesque church. Probably, they were made higher during the 12th century. In the staircase turrets your still see Romanesque windows with round arches with dividing columns.
Further, this church is a built according to a centralized pattern. This was already the fact in the Romanesque period. The current eightsided centralized building was constructed upon the basements of the ancient building. So it can be considered as a a reconstruction of the ancient building, but in an 18th century neoclassical style. This reconstruction was done short arfter 1750 under the leadership of J.B. Renoz. The scalemodels in the church clearly show how the construction changed throughout the history. You see how the concept of the centralized building building remained, how the choir was enlarged and how apsisses were added.
Notger seems to have been burried inside this church.
In fact, the chruch was a copy of the Paltschapel in Aachen.
The original entrance of the church was not found back. Maybe, as in the Palts chapel in Aachen, it was in the western tower. But if that were the case, this would have been the only church in the Mosane country having an entrance in the West-East axes.
According to some sources, Notger wanted to commemorate the Charles the Great. The model of the church fitted the cultural vision of the Ottones, fitting the Carolingian dynasty. But maybe there was something else. When looking at this Saint-Johns' church, the at that time existing Our Ladies' cathedral, the Saint-Lamberts' church and the Holy Cross church, there seems to be a link to Jerusalem. The same concept seems to have been used in other cities as well (like Utrecht).
Inside, the attention is attracted into the height, towards the dome of the centralized building.
But you should mainly pay attention to the 3 Romanesque, 13th century statues: the sad Holy Virgin, Saint-John the Baptist and the famous Sedes Sapientiae.
We also point to the nice confessionals, and the floor design.
Outside the church, pay attention to the late Gothic vaulting of the cloisters.