Welcome to the mobile app for Old St Mary’s Catholic Church in Detroit, a home for lovers of Catholic tradition, devotions, and Church music. Located in Greektown, Old St. Marys is the third oldest Roman Catholic Church in Detroit and the first German Church; built on the present site in 1841 when the total population of Detroit was just over 5,000. Old St. Marys is ranked #6 of 87 Must-See Attractions in Detroit by TripAdvisor.com.