"The Unprinted Mile" is a text document consisting of one line exactly 5,760 pages long. A standard piece of paper is 11 inches long, a mile is 63,360 inches long, thus 63,360 divided by 11 equals 5760, giving us our page count.
"The Unprinted Mile" is both a conceptual object and a physical object. The conceptual object exists only in the digital space, and the physical object can be born through the process of printing itself.
If one were to physically manifest "The Unprinted Mile", the document would be printed, and the pages would thus have to be laid on the ground, bottom edge to top edge for the entire page count. The end result would be "The Unprinted Mile Printed".