The lavish descriptions of the houses in this Millionaires's Row are meant to give us an insight into Dexter's mindset. When he looks at all this grandeur and opulence, he knows that this is what he wants in life. He doesn't want to be a humble store-owner like his old man; he wants to be filthy rich, to live in the kind of luxury mansion inhabited by Judy Jones.

But more than that, Dexter craves stability. And as the previous educator pointed out, Fitzgerald's description of the palatial Jones residence suggests precisely that. These people aren't just rich; they're old money, secure in the vast wealth they've accrued. As he gazes in awe-struck wonder at those solid walls, Dexter is given a tantalizing glimpse into another world, a world he so desperately wants to inhabit.

Judy Jones represents the female incarnation of the American Dream for Dexter, and her house symbolizes how industrial capitalism makes this idea possible. Part IV provides a passage that helps us with this interpretation:  “The dark street lightened, the dwellings of the rich loomed up around them, he stopped his coupe in front of the great white bulk of the Mortimer Joneses’ house, somnolent, gorgeous, drenched with the splendor of the damp moonlight.  Its solidity startled him.  The strong walls, the steel of the girders, the breadth and beam and pomp of it were there only to bring out the contrast with the young beauty beside him.  It was sturdy to accentuate her slightness—as if to show what a breeze could be generated by a butterfly wing.” Note here the romanticism with which he views her (“damp moonlight,” “young beauty,” “slightness,” “breeze”) and wealthy that makes her possible (“great white bulk,” “strong walls,” “steel of the girders,” “breadth, beam, pomp”).