The Codex Wall in “Assassin’s Creed 2” is a simple puzzle that appears very confusing if not approached in the correct manner. It needs to be completed to access the final mission. Ezio must have collected all 30 pages of the Codex before he can solve it. This becomes much easier upon reaching Sequence 14, because any remaining Codex pages are marked on the map at that point. Leonardo da Vinci needs to decrypt the pages before they appear on the wall. This happens automatically when you speak with him.
Look at the Codex Wall located in Mario’s office in Villa Auditore. A help bar should appear on the bottom of the screen that says “Codex Wall” and lists the commands you may use. If the bar does not appear, you are standing too far from the wall to solve the puzzle.
Press the “Y” button to activate Eagle Vision. Glowing lines appear over top of the normal writing on each Codex page inserted into the wall. You can ignore the writing on the Codex pages completely. The glowing lines are the only thing important to solving the puzzle.
Rotate all of the pages along the edge of the Codex Wall using the right and left trigger buttons. These pages have a border line, which makes them much easier to align with one another.
Rotate the remaining pages to line up the glowing lines to form a map of the world. The Codex Wall is solved once you have all of the pages lined up.
You can re-read the Codex pages on the wall by pressing the “A” button. This can be performed prior to reaching Sequence 14.