This month’s “Piece of History” is a picture taken June 6, 1957, of big band leader Duke Ellington talking to four people — Mr. and Mrs. Thomas Hoegen and Mr. and Mrs. Michael Ford — in Cedar Rapids. The couples were among the almost 700 people who came to hear and dance to Ellington’s music at the Elks Club, then at Hawthorne Drive and Water Street SW.The Thursday night performance was so successful that the club invited Ellington to open its dance season the following year.