A boulevardier is someone who strolls city streets for pleasure, and the speaker here seems to be exactly that. Walking isn't just a way to get somewhere, though. It's meant to "magnify my heart," as if each step makes the speaker's feelings larger and more alive.
The city they walk into is "of gold and bacon," an odd, funny pairing. Gold suggests wealth and glitter, while bacon is earthy, greasy, and comforting. Together they make the city feel both dazzling and everyday, something you can smell as well as admire.
The last lines turn on a clever wordplay: "I am not without life / like the play in plague." The word "play" is hidden inside "plague," so even in something deadly, there's playfulness. The speaker claims the same: they are alive, and a little mischievous. The mood is upbeat and curious, with a light, wry humor running through it.