The final two monuments were unveiled Tuesday. They include glass towers representing the World Trade Center and a fountain in honor of United Airlines Flight 9, which crashed in western Pennsylvania.
On hand for the dedication was the widow of San Jose native Jason Dahl, the pilot of Flight 93.
"This is the time I get to say something happy and the pride that I feel, not just for our loved ones, but all of the airplanes," said Dahl's widow.
The fair's 9/11 Memorial Plaza started in May of 2002 when arrangements were made to bring a piece of steel beam from the World Trade Center to Cal Expo.
The memorial now includes several monuments and exhibits.