In just three lines, the poem sets up a quietly unsettling picture. The speaker says "we" watched a city build scaffolds, and the scaffolds are for "all who read books." The title, "Public works," makes it sound like ordinary civic business, like roads or bridges or repairs, but the thing being built is not for construction. A scaffold can hold up a building, yet it is also the platform for a hanging, and the poem never says which it means.
That ambiguity is where the mood comes from. The tone is flat and matter-of-fact, as if this were just another project the city got around to. The speaker doesn't protest or explain, only watches, and the "we" suggests a crowd standing by. Judging by the wording, the feeling underneath is dread and a kind of helpless complicity. Readers are being singled out, and the quiet reporting makes that feel more chilling than any outcry would.