Corner of John and Front Streets, Cincinnati Ohio: J. A. Fay & Co circa 1866. Single sheet, 43 1/2 x 26 3/4 inches. Previously folded, with minor dampstaining, tearing at the folds and minor edge losses. Unrestored, should be laid down archivally for preservation purposes. Likely a distributor or large reseller advertising broadside given it's large size. Good. 
Jos. B. Boyd, Printer, 25 West Fourth Street lower left. Winner of US Agricultural Society "Best Woodworking machinery" in 1860 (emblems upper right and left). Many of the machinery illustrations show patent dates, ranging from 1858 to (mostly) 1862/63. There is a hand written note "Wrote for this ??" above the Upright Saping and Moulding Machine with 8/66 (which we presume is 1866). Many of the illustrations are identified by the artist/engraver(s).
Given the turmoil and lack of business around the civil war and the company re-organization, we feel it appropriate to date this broadside to circa 1865. It is unlikely that the company would expend significant resources printing this large a broadside during the war. The fact that a number of Abraham Lincoln items printed by Boyd are dated 1865 further supports this hypothesis.
The company history of Fay & Co is very complex, with various owners and partnerships through the beginning of the civil war (see vintagemachinery org for the best summary we could find) According to that source, the firm (which previously had been active in at least Cincinnati Ohio, Keene NH, Vermont, and Massachusetts) was dissolved and it's name and assets (sans the NH and MA operations) were purchased by a group of agents. They re-established the firm and the Cincinnati Ohio location became company headquarters. After the reorganization the company thrived until it's merger in 1893 with The Egan Co.