From American Heritage: America’s Top 10 Public Works Projects

- Click here for the article. 

Here's the list, its a good one, but I can think of a few more: 

- The National Road
- First Transcontinental Railroad
- Hoover Dam
- Oregon Coastal Highway Bridge System
- Air Traffic Control
- Lincoln Tunnel Nearly
- The Tennessee Valley Authority
- Interstate Highway System
- The Big Dig
- The Internet