Because there is an hidden secret ECHO in The Division’s Chelsea district at the very beginning of the game, a lot of people are asking how to get there and how to activate this ECHO in order to be able to unlock the “Shadows of the Past” achievement.

You won’t be able to reach that one until you complete all story missions first and accept a side quest called “Unknown Signal”, which will lead you to the desired location. Once you are there you can activate the ECHO and the “The Final Curtain” achievement will be automatically unlocked (full list).

The following video shows exactly where you can find this collectible and how to get there.