The distant city has a decaying skyline beyond the hills; people suspect its glass-and-steel buildings once housed people aboveground.
A decaying city skyline is visible beyond the hills. People suspect that its distant glass-and-steel buildings once housed people aboveground, but that interpretation is uncertain.
A decaying skyline of glass-and-steel buildings is visible beyond the hills.
It is a visible remnant of a possible aboveground place of habitation.