Tenor or Tenol church in Eidsberg was located on the estate of Slitus and is believed to have been erected at the end of the 13th century. It was a long stone church and is believed to be the only medieval brick church located in the countryside, outside the cities. The church had a short, rectangular nave and a narrower choir that was originally roughly square before being extended to the east. It has been redone on the choir arch so that the choir has gradually opened up to the full-width ship. The church was closed down after the Reformation and was deserted from the middle of the 16th century. In 1619 it was closed and overdue, but approx. By 1700, the walls were still pretty much whole. The church key, a Madonna figure and a chandelier are still preserved.
Today, there is little more than the foundations left; only a short piece of the wall protrudes over it. The ruins were archaeologically surveyed in 1953 and - 56 and the walls were restored by the National Antiquities Authority and Østfold County Municipality in 2010.
The area is today a free area with public access. Limited parking at Slituveien.