Where It All Goes Down
Chester, England and Paris, France (and shadows of Woollett, Mass.)
From the moment he lands in Europe by himself, Strether experiences a sense of freedom that he hasn't felt in a long, long time. And that makes a lot of sense, since his usual life in Woollett, Massachusetts is totally dominated by his fiancée, Mrs. Newsome.
Strether's feelings of newfound independence only get stronger when he reaches the beautiful city of Paris. It sometimes sounds like the guy gets downright drunk by looking at all the sights, as the narrator notes, "These first walks in Europe were in fact a kind of finely lurid intimation of what one might find at the end of that process. Had he come back after long years, in something already so like the evening of life, only to be exposed to it?" (1.3.15).
The thing that Strether is realizing "after long years" is that there's a beautiful, exciting world beyond his sleepy hometown of Woollett. But Strether's cautious approach to life has always prevented him from taking risks and experiencing new things. He's sad to think that it's only in old age that he can begin to appreciate how much he has missed out on.
What Strether truly reacts to is the contrast between the cultural history and beauty of Paris and the boring predictability of Woollett. And yes, James is using the differences between these places metaphorically, too, as he writes of Paris, "It hung before him this morning, the vast bright Babylon, like some huge iridescent object, a jewel brilliant and hard, in which parts were not to be discriminated nor differences comfortably marked" (2.2.8).
So Woollett comes to represent all the safe, yet boring decisions that has led Strether to feel like he's wasted his life. Paris, on the other hand, represents the cool, interesting life that got away. And now that Strether is in Paris at an older age, he finds it difficult to let go of the place. In fact, he'll do nearly everything to stay there for one more month, even end his engagement to Mrs. Newsome. Which isn't too big a loss, he realizes by the end.