Once finding all of the pieces to unlock a code, you are given a note from one of the inhabitants of the compound. This letter hints at Pieces of Eden trying to be uncovered and gives you the access code to the elevator. The code is 122112. This code can be decoded further, the 21st of December, 2012 is a Mayan prediction, but is the main event of Assassin's Creed Series involving Desmond (Main Character ) fighting templars to find the Pieces of Eden, and save the world from the date of 12/21/12, also known as the Apocalypse. See video of the mission on the right: