Vatican Vault

The Vault is one of the "Temples" left by Those Who Have Gone Before, but their exact purpose is still under speculation. Minerva's message is that the Vault's contain some sort of assistance or research in staving of a repeat of the Catastrophe that has occured before.

It appears that only a combination of different Pieces of Eden can open it, and are built to only allow specific people to enter, such as Ezio, who was named a "prophet." In Assassin's Creed 2 Ezio enters the vault under the Vatican and opens the Vault door by holding the staff with has a Pieces of Eden attached to it. In the Vatican vault there are images on the wall that only appear when Ezio comes near them detailing other Vault's locations; this is the true "data" of Minerva's genetic transmission. We can clearly see a step pyramid so there's the possibility of a Vault in Mesoamerica or a ziggurat of Mesopotamia.