US Geological Survey
Usgs: Virtual Tours of National Parks
Excellent site to discover the National Parks from the convenience of your computer. Click on each park for a virtual tour, many in 3D, many offering historic photos. Dig deep into our national geologic story.
Siteseen
Siteseen: American Historama: Hoover Dam
Article provides statistics and facts about the Hoover Dam, the powerplant, and Lake Mead.