User blog comment:Gundam Legilis/Welcome to Beacon In Depth - The aesthetic/@comment-99.102.108.17-20140805170116

Whenever I think of "Green Light," I think of the Great Gatsby. Hopes, dreams, and guiding light. But, err, anyone who read GG knows how that turned out.

But that's just me, haha :)

Maybe the tower and the green light serve as a literal beacon? I mean, the office is pretty high up, there are clouds, and also airships at that level so they would need something to prevent any unfortunate accidents...

I can't think of any other possible reason for the light, other than it being a part of some defense mechanism against the Grimm. It's definitely not just decor- can you imagine how annoying it would be, trying to do work in your office but this huge green light above you was flashing everywhere?