I can't tell what we're seeing. It looks like a human city but some things are missing or might be missing. The curve in the background looks like part of the horizon, it looks like the edge of an artificial... thing the city (or group of buildings) is on, and it looks like the wrong slope for a Halo... to me, this looks like human or maybe Forerunner stuff on the Ark (or on an Ark).
OK now I'm looking at the full-res version... the curves that some things have don't look Forerunner... OK there are signs, in English even, so it's obviously human... that black curve still looks unnatural to me, and not human-made.