Hoover Dam: True Giant (5) tv-pg Play video Select your TV provider to log in to have full access to videos Select your TV provider See all providers Don't see your TV provider? Learn more You can access this video on the free HISTORY® apps. *You must verify your TV provider towatch this video on the App Your Parental Control settings do not allow you to view this content. Hoover Dam: True Giant (5 min) tv-pg The awe-inspiring Hoover Dam was built in the 1930s from enough concrete to create a two-lane highway from Los Angeles to Boston. How long did America's largest, man-made reservoir take to complete?