The Great Central Fair in Logan Square, 1864. (Library of Congress)
The structures housing the Great Central Fair were as spectacular as the contents. Built in just forty working days by volunteer craftsmen, the 200,000- square-foot complex featured Union Avenue, a 540-foot-long, flag-festooned central hall over which soared gothic arches. The Avenue was flanked by rotundas to the south and north and other outbuildings, all interconnected by bustling exhibit corridors. Presiding over the entire Fair site was the Stars and Stripes, unfurled on a 216-foot flagpole.