The author supports their claim that "The Inca were great builders" by talking about how much they loved stone and took pride in their work of building temples and fortifications. What they built was sacred to them and they put extraordinary effort into it. According to the text in paragraph 12, it says, "Constructed without mortar, the joins between them are so tight as to deny a knife-blade entry. A vast labor force was required. There are records of 20 men working on a single stone, chipping away, hoisting and lowering it, polishing it with sand, hour-by-hour, for an entire year." The Inca took building very seriously, and the author shows this by providing more detail into the intricates of the design and the amount of time and effort it takes for them to make these creations.
I'm not completely sure about all these, but I'd say that these phrases best support the author's purpose of creating a positive image of a town: 'live in harmony', 'blaze of color', and perhaps 'hillside…
Henry Wadsworth is using a poetic technique called enjambment in this excerpt. Enjambment means that you continue your thoughts from one line into the following one, or from one stanza into the next one.
