Summary I videotaped this from TV and only kept certain portions. The episode covered, at least: . Stone arch bridges, some are still in service and outlasted iron bridges. The one arch Carrolton Viaduct (1829) is the oldest in the U.S., and the 8 arch Thomas Viaduct (1835) just west of Baltimore is the next oldest. The Rockville Bridge over the Susquehanna 1902 replaced earlier wooden (1849) and iron (1879) bridges. Tunkhannock Viaduct/Nicholson Bridge 2,300 feet length, 240 feet above the community of Nicholson, PA., built in 1915 was given as the ultimate example. . Snow sheds . Alleghany Portage R.R. which pulled canal boats over the mountain ranges. John Augustus Roebling developed a steel wire for them to use and replace the Russian hemp ropes which broke. The steel wire was later used at the Niagara Falls and Brooklyn Bridges. . Horseshoe Bend . Centralized traffic control, operations center . The Chunnel and earlier attempts at digging tunnels across the English Channel.

• Documentary
• History