The chapel now houses the original 1794 plan-relief of Bitche. The plan, executed on a scale of 1:600, meticulously recreates the citadel in its 18th century environment. Extracted, among others, from the Parisian conservatory of relief plans during a Prussian seizure in 1815, the model was offered by the German Emperor William II to the Metz Museum in 1903. It has been kept in Bitche since 1923.