One of the world's greatest engineering feats, the Panama Canal, recently turned 100 and NBC News recently posted a pictorial essay that captures in at least a small way the challenges facing engineers and workers, not the least of which was supplying concrete to the site. How much concrete? At the Gatun Lock on the Atlantic side of the canal, workers poured enough concrete to build a wall eight feet wide, 12 feet high and 133 miles long. Read more and view pictures.