During the Second World War, St. Petri suffered severe damage and the restoration was not completed until 1987.
The effect of the simple space of the five-aisled hall church is very well emphasized by the special architecture.
In the 15th century it was expanded to its current appearance: a Gothic, five-aisled hall brick church with five bays.
This also included the organ front, created by the carver Tönnies Evers the Younger, and the important brass gravestone of the councilor John Kliingenberg.
The baroque baptismal font of the church, donated by the councilor Johann Philipp Lefèvre, was preserved.
The instrument is situated in the north aisle and was constructed by the organ building company, Hinrich Otto Paschen, based in Kiel.