Eads Bridge - St. Louis MO 4

They don't build them like this anymore. Built in 1874 this antique bridge crossing the Mississippi River from Illinois to St. Louis MO has 3 arches constructed of iron and piers built out of limestone. The bridge is still in use today and in pretty good shape carrying auto traffic and light rail trains across the river. It was an engineering marvel achievement for it's time and a great relic of the past.