UNSC structures on Requiem

[HaloWithStyle]

So how come all the human buildings etc on Requiem look like they've been there for decades when MP and Spartan Ops takes place only 6 months after the campaign? There's even rocks forming over walls like tree roots growing wild.

[Zuko 'Zarhamee]

So how come all the human buildings etc on Requiem look like they've been there for decades when MP and Spartan Ops takes place only 6 months after the campaign? There's even rocks forming over walls like tree roots growing wild.

Those structures were built by the Forerunners, not the UNSC.