Additional information:It’s the big archway in the Glarus Valley.
On the Empire side: fly to Elysium Thranta. It’s just NE of Outpost Ghrent. The flight will take you up onto the archway to the Heroic area; and there you’ll get the codex.
On the Republic side: Currently non obtainable, since you need quest and a taxi to get to this location, and there is none for Republic side.
We would like to thank Adam, Nanta and Clover for additional information.
Original Game Codex TextFor millennia, the Elysium has served as the symbolic center of Alderaanian politics. Years before the capital city was founded, the various noble houses met in the Elysium to elect and anoint their first king. Until recently, every dispute over succession in Alderaan’s history had been peacefully resolved within its stone walls, and the houses’ greatest treasures were placed in Elysium vaults as a symbol of trust.When Gaul Panteer was assassinated and Alderaan’s ailing queen passed on in a mysterious transport crash, the parliament assembled in the Elysium to elect a new sovereign. It was then that House Thul made its move, returning to Alderaan after decades of exile. Violence and accusations erupted almost immediately, and since then, the Elysium has remained an empty, forgotten symbol of Alderaanian unity–its ancient halls cracking as distant bombs fall, and its beauty quickly fading.