Yeah, that’s how ruined cities work, too. Valuable artifacts just got thrown into the Artifact Corner. Don’t ask us why, we’re not city planners.
If you’re interested in looking through these ruined subterranean structures, you can take a full look through the tour guide on the official site (we’ve got the images just below, as well), where you can learn a little more about the various locations now found away from the gaze of the sun. There’s no mention of being able to buy up ruined portions of the city for gentrification and/or installing a Whole Foods, but we can assume.