The civil engineer is often fingered these days as Ecological Enemy No. 1 for his enthusiastic participation m the rape of the environment. But to an earlier, less beset society, with fewer people and afar less potent technology, the engineer was more than a popular hero; he was the epitome of an age. The conquest of nature was the national ambition, and the civil engineer was the man who kept the state of the Union up to the state of the art.

In 1966 the American Society of Civil Engineers began a project to designate surviving souvenirs of the fruitful nineteenth-century collaboration between engineering and entrepreneurship.

Included in the list of seventeen railroads, canals, bridges, tunnels, and dams so far designated:

• • Bollman truss bridge, Savage, Maryland, the last remaining example of Wendel Bollman’s pioneering design for an all-metal bridge. Between 1850 and 1870 one hundred Bollman bridges were built to carry the Baltimore and Ohio Railroad across the Alleghenies into the opening West.
• • Union Canal Tunnel near Lebanon, Pennsylvania. Dug in 1825, the tunnel burrowed through 729 feet of rock to speed water traffic between Philadelphia and Harrisburg.
• • The Acequias, San Antonio, Texas, narrow canals built by the Spanish two hundred and fifty years ago.
• • The Durango-Silverton branch of the Denver and Rio Grande Western Railroad, a breath-taking marvel that clings to the side of the Las Animas canyon and carries capacity tourist crowds. It is the last nonmuseum narrow-gauge road in the United States.