Old St Mary’s is the third oldest Roman Catholic Church in Detroit and the first German Church. It was first built on the present site in 1841 by a parish of German Catholic immigrants at a time when the total population of Detroit was not much over 5,000. Not including labor, the original brick church cost a little over $239. The present church, replacing the earlier structure, was constructed in 1884, and styled in Victorian Gothic by Peter Dedericks, a native architect.