Old St. Mary's Church - Credit: Wikimedia Commons
Old St. Mary's Church in Milwaukee, Wisconsin was built in 1846 and 1847. The parish was founded a year earlier, by German Catholic immigrants. It was the proto-German church of the Archdiocese of Milwaukee. The city had been incorporated only the year before, and Wisconsin had not yet become a state. Old St. Mary's is the oldest church still standing in the city. The building was listed on the National Register of Historic Places in 1973. Read more on Wikipedia
Source: en.wikipedia.org