Diedrich Augustus Bohlen (January 17, 1827 – June 1, 1890) a native of Cadenberge, Kingdom of Hanover, immigrated to the United States around 1851 and founded D. A. Bohlen, Architect, in 1853 at Indianapolis, Indiana. In 1971 it became Bohlen, Meyer, Gibson and Associates, and is among the oldest architectural firms in the United States still in operation. Bohlen is best known for introducing the German Neo-Gothic architecture style to Indiana. Bohlen and his firm specialized in institutional projects, especially civic, religious, and educational buildings. More than forty of the firm's projects are listed on the National Register of Historic Places, including several of D. A. Bohlen's designs: Morris-Butler House (1864); Saint John the Evangelist Catholic Church (1871), its rectory (1863)