Kate Shelley High Bridge, Iowa

One of the highest and longest double-track rail bridges in the USA. It was completed in 1901, officially called the Boone Viaduct. It is 185 feet tall over the river, and is 2,685 feet long. It is on the main east/west route for the Union Pacific, the Overland Route, between Chicago and the West Coast. A new bridge was constructed next to it in 2009, slightly taller and longer than the original one, which remains next to it, unused.