Eesfet Oon-m'Aa Poo

Eesfet Oon-m'Aa Poo is an Isu vault located along the Nile in Egypt, under the Great Sphinx of Giza. This vault was locked and could only be accessed when the twelve Stone Circles scattered throughout the region are activated.

Around 48 BCE, the vault was visited by the Medjay Bayek after he activated all the Stone Circles. Once into the vault, Bayek found an Isu Armor left by Those Who Came Before and activated the vault's pedestal, which in turn started a recording made by the Isu one hundred and nine days after the Great Catastrophe intended for Layla Hassan, who was reliving Bayek's memories in 2017.

Reference

 * Assassin's Creed: Origins