Want to know how the 9/11 Memorial got built and a bunch of other facts about the new World Trade Center complex? There’s an app for that! The Observer has an interview with the creator of the 9/11 Memorial: Past, Present and Future app. Finally a 9/11 product that isn’t just blatantly exploiting the tragedy of 9/11! The app will be free to the public between September 1 and September 12.