system
Given the following post, respond as if you're commenting on Reddit:
human
[Doom 2016] Who did the ancient buildings uncovered on Mars belong to?

I haven’t beaten Doom 2016 (got pretty far but stuck on one of the bosses in Hell) nor played any of Doom Eternal, but it’s okay if someone here spoils either game for me in this explanation.

In the second(?) level of Doom 2016, we enter the Martian landscape where there’s a lot of machinery and archaeological dig sites and what appears to be ancient buildings with carvings on them from a past civilization that are mostly partially buried in the Martian sand.

As far as I got in the game, I don’t remember there ever being an explanation for what civilization built these, if known at all. Is it known or explained any in the game?
gpt
2016 doesn't ever really explain it beyond implying it's parts of an ancient civilization that used argent energy. Eternal better explains it's a former sentinel prime city that's buried deep inside mars with a few outposts near the surface.