Together with the Romanesque vault and a round window from the same period, the fortified church tower is the earliest witness to Keilhaus' history. It suggests a medieval church, on the east side of which there was probably an apse. In the 18th and 19th centuries, the church took on its characteristic form. The baroque tower dome was added in 1759 and a new nave was built in 1844. Some of the church's furnishings show the connection to the neighboring Fröbel School. The altarpiece, for example, was painted by a former pupil of the school, Friedrich Unger. It shows Jesus blessing the children. The faces of the disciples bear the features of Fröbel's companions: Middendorf, Langethal and Barop.