The Belfast Opera House was built in 1866-1868 and served as a venue for various entertainments, sports, lectures, and even basketball throughout the 19th and 20th century. During World War I it served as the armory and training center. Following the death of Frank D. Hazeltine, Lieutenant 101st Infantry, on the battlefield of St. Mihiel, France on September 12, 1918, it was proposed to establish an American Legion post in Belfast. The post was named in Frank's memory and its first location was in the Opera House. In 1926, a more permanent home for the Frank D. Hazeltine Post #43 opened in the former North Church located at the corner of Church and Market Streets. Today, the Opera House awaits restoration.