In addition to the symbolism found in the title of Fitzgerald's "Babylon Revisited"—Babylon being a word for aspects of a society that are degenerate (Baker's Evangelical Dictionary of Biblical Theology)—the Ritz Bar is also a symbol of the dissolute lifestyle of the expatriates who frequented it in the 1920s. Specifically, it symbolizes the profligate style in which Charlie Wales engaged, as it represents the irresponsibility wealth allowed him, as he and his friends would pay hundreds of dollars just to hear a song.
Interestingly, the narrative of the story begins and ends with scenes in the Ritz Bar; thus, this setting frames the narrative, lending important significance to it. Charlie has his one drink there now, but he senses the bar has changed since his younger days there: "[t]he stillness in the Ritz was strange and portentous." The mood in the bar is somewhat like the mood one feels upon going back to a former home, because one can never really return since changes have taken place in both the environment and the person.
It was not an American bar anymore—he felt polite in it, and not as if he owned it. It had gone back into France.
Because things have changed, it is spiritually dangerous to try to return. Dangerously, then, Charlie sits at the Ritz to try to recapture a past he has lost. He asks about some old acquaintances when he first arrives and gives the bartender the address of his brother-in-law's place where he is staying. This act turns out to be a fatal mistake. The old acquaintances, Duncan Schaeffer and Lorraine Quarries, obtain this address and appear in an inebriated state at the Peterses' home just as Charlie is about to win over his sister-in-law enough to be able to take his daughter Honoria to live with him in Prague.
The next day, Charlie's brother-in-law Lincoln phones and tells him he will have to wait another six months before asking Marion again about Honoria. Charlie returns to the Ritz, where he and his friends were once "a sort of royalty, almost infallible, with a sort of magic around us."
Now, there is no one Charlie knows and the magic is gone. Still, he has a desperate need to hold on to the past, and he must revisit the Ritz despite his having been exiled from his old life with Marion's rejection. As the memory of the old days "swept over him like a nightmare," Charlie's former favorite haunt is, nevertheless, the heart of his past when his wife was alive and he was happy and confident. As he has his one drink, Charlie engages in a sad reverie where once he was filled with gaiety: "He would come back some day; they couldn't make him pay forever."