Story related, cannot be missed.
********SPOILERS********
After the first mission of the game (Reach for the Stars) in which you fight a giant machine snake/cobra at the end you will return to Meridian for the second mission (The Point of the Lance). Once completing this very easy dialogue mission a cutscene will play of Aloy traveling across the land. You will then meet an elevator operator who will ferry you down to ground level. The Trophy unlocked for me soon after entering the elevator.