St. Mary Parish not only has the distinction of being one of the oldest parishes in the Archdiocese of Cincinnati, but one of the oldest in the state of Ohio.
It is one of two Catholic parishes in Piqua, the other being St. Boniface Parish. St. Mary’s congregation dates back to 1843, with the original church being dedicated March 8, 1846. At that time most churches were frame, but St. Mary was brick and thoroughly equipped. Extensive remodeling was planned for the church in 1898. However, after work progressed, it was decided that the church would be enlarged to include a cellar. This work was completed in June 1899. An extensive remodeling project to update the church was completed in 1979. The latest remodeling and painting project was completed in 2007.
Today we enjoy a beautiful edifice dedicated to Our Lord and cherished by approximately 1,700 St. Mary parishioners.