Mission 3 Optional: Destroy the Hidden facility

Where is the hidden facility, I think I’ve been all over the map, can’t fins it, got all the other optional objectives done

To the south of your main base, you need to fly there as it’s an island. The south is the cliff, if you have the bottom edge of your screen aligned with the cliff, then if you scroll down you see forerunner architecture underneath your base. Continue scrolling down and a little to the right and it’s there.

Nevermind, I found it all the way on the bottom of the map