One of the great marques in vintage motorcycles, the innovative four-cylinder Henderson, was manufactured in Detroit from 1911 to 1918 and then in Chicago from 1918 to the brand's demise in 1931. In Detroit, the factory's address was 268 Jefferson Avenue. My question is: can anyone tell me how this address translates to the current numbering system and where this factory was located? I'm sure the building is long gone, but what is there now?