5 scenes in Robert Lowell's For the Union Dead

"For the Union Dead" is one of Robert Lowell's great poems, and it means much more, I think, to a reader who actually knows the Boston landmarks, has seen the St. Gauden's relief sculpture in memory of Shaw's Black Civil War battalion - when I first read the poem these places meant nothing to me, but now they're part of my lexicon of memory. The poem has, by my rough count, five elements: 1. the ruins of the South Boston aquarium (which provides access to a memory of Lowell's childhood and also the imagery of bubbles rising, that Lowell will return to at end of poem) - this location isn't very clear to me and, I think, wouldn't be particularly near the Boston Common - I actually wonder if the poem would be stronger if he'd sliced out the references to the aquarium, giving it more unity of place?, 2. the Boston Common, which at the time of the poem is being ripped apart to build the underground parking garage - I wasn't around then, but I imagine it was seen as a great project of civic betterment, which Lowell looks on with horror, bringing more cars into the city - he deftly describes how the underground work shakes the foundations of everything, including the nearby State House, and that leads to 3. the St. Gauden's bas relief, propped up by a plank, and this is the heart of the poem, Lowell thinking about the bravery of leading a near suicidal mission during the Civil War, and the heroism of Shaw (and his troops) and the scorn he must have faced for leading a "Nigger" battallion - and this is his monument, placed in jeopardy by the shovels gouging the earth - which leads to a break in the poem of one stanza, 4. describing the typical New England green with churches and their spires of "sparse, sincere rebellion" (great phrase) - so different from this Common, being torn apart, and at last, near the common, a store window on Boylston street showing a safe that has supposedly endured a nuclear blast - linking the Civil War to the then most-recent war - and showing the contemporary exploitation of images of death and the tawdriness of the street culture, even in so-called cultured old Boston. Lowell touches on many themes in this poem, but the overall, I think, is the valor of sacrifice and its ultimate meaninglessness - the monuments propped up by a plank while the heart of Boston is ripped apart in the name of progress.