Assassin Tombs
The Assassin's Tombs are located across the Northern section of Italy, and contain the remains of six of the greatest of the Assassin's Order. The tombs were created as a dedication to their lives, with the bodies moved from their original graves to these Tombs. The crypt of each contain an Assassin's Seal, which, when accumulated, unlock a gate in the Sanctuary of the Assassins underneath Villa Auditore, hidden behind which is the Armor of Altair, the strongest armor in the game.
The Seals
The Assassin Tombs are hidden areas which can be found throughout Assassin's Creed II,each contains a seal. Each seal you collect will get you nearer to acquiring the Armor of Altaïr which is in the sanctuary in the Villa Auditore. It is behind a bookcase in the room with the codex wall, Uncle Mario will lead you there, allowing you to start the quest on gaining Altaïrs Armor, which is required to progress the game. Every seal has a different sign on it which represents the 6 legendary Assassins
Armor of Altair
Main Article: Altair's Armor
This armor is the best armor you can find in Assassin's Creed II, the armor was made by Altaïr, it has no ties with the Altaïr's armor in the first Assassin's Creed. It is unbreakable and cannot be mixed with other armors and no dyes are visible (except for the inside of the hood) on the armor, if you try then it will change your other colour armor to that other colour you chose. If you get this then the last thing you need to do to make your assassin perfect is the Sword of Altair.