The candied redolence of honey-roasted peanuts floats into the urban breeze at Downtown Crossing near the famous Filene's Basement department store. Pushcart vendors lure hungry pedestrians with Italian sausages, burritos and steaming fried dough. A street musician plays a percussive empty-bucket sonata in front of Macy's. The flurry of humanity here is as diverse and spirited as anywhere else in the city. A couple of blocks away on shadowed West Street, writers, readers and curious passersby thumb through used books on discount racks outside the Brattle Book Shop, one of the oldest bookstores in the country. High above within a slate-tinted glass tower, someone is enjoying the royal treatment at the new Ritz-Carlton hotel-the proverbial top of the ladder. Actually, such a proverb is still in-the-making, as Boston's newest Old Neighborhood, The Ladder District, is enjoying a swift revitalizing boom that has shifted affections in this city.

We say old and new because the sobriquet "The Ladder District" was actually part of the local lexicon almost 75 years ago, after which it was reduced simply to "Downtown Crossing," the focal point for shopping at Summer and Washington streets. But it was those narrow, perpendicular side streets, which appear from above as rungs of a ladder, that gave the neighborhood its original name. They are held together by parallel Tremont and Washington streets, extending from Chinatown to Downtown Crossing.

Now, seemingly overnight, the old name is back and new businesses are in. There is night life where before there were dark alleys. There is commerce where buildings had been boarded up for decades. The Ladder District is alive in a distinctly urban way-a throwback to a time when Downtown was the center of cultural life. Take, for example, the new 19-screen Loews Cinema on Tremont Street with its '50s-era marquee lighting, or the highbrow, lounge-style billiards club Felt, which opened only weeks ago on Washington Street.

Then there's the dining. Two of the hottest new restaurants in the city, Mantra and Limbo, have settled on Temple Place, which was named after the famed Masonic Temple where Ralph Waldo Emerson used to give Transcendentalist lectures during the mid-1800s. Mantra, the swanky Franco-Indian eatery which opened last year, has drawn the city's glitterati to the neighborhood and earned national praise, while the new jazz club Limbo cooks up Italian cuisine and presents cool live jazz in a plush atmosphere. Most notably, the old Brahmin mainstay Locke-Ober, in a telling change of theme from it patriarchal history, re-opened under the guidance of local celebrity chef Lydia Shire, who reinvigorated Boston's dining scene at the heralded Biba.

If there is a theme to the Ladder District-and a distinct charm-it is contrast. The neo-modern Ritz hotel and townhouses on Avery Street, which house the upscale Jer-ne restaurant and the trendy Sports Club/LA next door, stand on part of what used to be known as "The Combat Zone"-a formerly seedy section of town that still has a gritty character to it.

So how was the old moniker "The Ladder District" resurrected, anyway? The idea came unwittingly, says local PR executive Rosanne Mercer, "from a gentleman at City Hall who had obviously been working there for a long time." She and the owners of Limbo were applying for a business license when they mentioned their Downtown Crossing address. The clerk replied, with grandfatherly obstinance, "No, that's The Ladder District." They realized they had just discovered the concept that would return the promise of this forgotten neighborhood and unite their business with all the others: What's old is new.