The 10th anniversary of the terrorist attacks of 9/11 is a few days away. The 911 Memorial: Past, Present, and Future app for iPad explores the World Trade Center events. More than 400 pictures and 40 videos allow you to see the construction of the Twin Towers and view them as they were before that fateful day. You can also see how 9/11 unfolded, including never before seen video of the attacks on the World Trade Center. Other information covers the cleanup and recovery phases and the construction of the Reflecting Absence memorial and the museum being built on the site. The 911 Memorial: Past, Present, and Future app is free in the iTunes app store.