The tour brings you to the North End, to a nondescript brick building washed out and weathered with white-framed windows.
''Picture this now," says one of your guides, Robert Fitzpatrick, former chief of the FBI's organized crime squad in Boston. ''It's Jan. 19, 1981, and the streets are empty, cold wind blowing down. Two guys, a gal coming down the street, and they're both swigging whiskey. They hop up these stairs, and they pick that lock and then bang, we're inside. And just like that. Imagine that, FBI agents were now in Mafia headquarters."
This is no bus tour. It's MP3 -- downloadable, mod, off the beaten track. Some say it's the future of the tourism industry, a new-age take on an age-old tradition.
For decades, Boston's tours have been a staple for a city steeped in rich history. The steel duck boats and trolleys quickly distinguish locals from visitors. But some tour companies say the conventional group-follow-the-leader routine isn't selling well with the younger set, which is less inclined to sightsee with a horde of strangers.
So how do you make historical tours more hip? Just add an MP3 player, some companies have concluded. New audio tours allow individuals to explore without looking like daytrippers.
''Every tour in Boston is made by old people," said Rob Pyles, who launched his audio tour, Audissey Guides, in September. ''Younger people want something that's dynamic and edgy. They don't want to look like a tourist in a big herd."
In his Audissey Guides tour, Pyles narrates and Bostonians interject with dramatic tales of history while guiding listeners to 27 sites, beginning in Boston Common and ending at Long Wharf. The 78-minute course includes covered cobblestone walkways and shadowy back alleys. The music and sound effects make the experience feel like a virtual movie.
At the Omni Parker House Hotel restaurant, for example, the sounds of hushed conversations, clinking glasses. and a speech by Malcolm X, who bused tables there in the '40s, are in the background. A horse gallops and a bell tolls when you're standing at the old brown clapboard home in North Square where Paul Revere lived.
The tour is the latest in a city with a long reputation as a leading tourist destination, attracting some 17 million visitors last year, and an abundance of companies and foundations that offer tours by trolley, foot, or boat. Gimmicks range from costumed historic characters to the ''quack quack" cry of Boston Duck Tours.
Tourism officials say many are going to have to update if they are to attract the 18- to 27-year-olds, who are less likely to be interested in the old ways of seeing sites.
''That's not how they live their lives," said Patrick B. Moscaritolo, the chief executive officer at the Greater Boston Convention & Visitors Bureau, a nonprofit sales, marketing, and promotional agency that brings visitors and special events to the Boston area. ''Young people today are doing five things all at the same time. They've grown up with Game Boys and MTV and text messaging. If we don't engage them on their terms, then we run the risk of losing them as visitors."
Even some of Boston's oldest tour organizations are heeding that call. When this year's tourism season begins next month, the 55-year-old Freedom Trail Foundation, whose staple has been tours led by costumed guides, will introduce two-hour MP3 audio tours that visitors can do on their own. Visitors will be able to download the audio tour from the foundation's website and rent or buy MP3 players. Tour coordinators are also arranging to have snippets of the tour available through cellphones.
Such prerecorded tours offer benefits like an ability to give customers more information than is typically practical in traditional guided tours, said Mimi LaCamera, president of the Freedom Trail Foundation. They also provide the added entertainment of background effects.
''That's what young people are demanding from their cellphones and their iPods," said Mimi LaCamera, president of the Freedom Trail Foundation.
Not everyone in the trade agrees that MP3 is the way to go, however. Bob Schwartz, assistant director of marketing and sales for Boston Duck Tours, said that audio tours lose the excitement and sense of connection that a tour guide can create. He said the company has been successful attracting young tour-goers with its approach: There are 24 of the World War II amphibious landing vehicles in the city, he said, each with a different guide that brings a different element to the tour.
''You can't put all that information on one audio tape and expect it not to be three days long," he said. Plus, he added, ''you can't ask questions to an MP3 player."
Others simply are not inclined to change formulas that have worked for decades. Boston By Foot, a nonprofit whose 90-minute guided tours are aimed at history buffs, has not changed substantially in 30 years.
''It's very direct, pure, and simple," said Dana Robbat, the company's executive director. ''We feel like we do have our own niche."
Meanwhile, Discover Boston, an 11-year-old tour company, has gone a different direction altogether. By day, it offers multilingual trolley tours. But when night falls on weekends, the trolley is transformed into a party bus with plasma televisions, a deejay, a dance floor, and strobe lights.
''It's like a nightclub on wheels," said owner Gideon Oknin, who began the party buses last year. ''It's boosting up my business."
For all the guessing about what the next generation of tourists wants, young people express widely diverging preferences. Tracy Borneman, 26, who was visiting from Westminster, Md., said she would prefer an MP3-guided tour, which would let her go at her own pace.
But others, like Danny Clark, a 25-year-old Boston native who has taken the Duck Tour, said they'd rather have a live guide.
''If I become further interested in something," Clark said, ''I'd rather have someone there."
Whichever view prevails, specialists say the gadgetry of the Internet age is likely to play a larger role.
''Technology is becoming the third 'T' in travel and tourism," said Paul J. Sacco, executive director of the Massachusetts Office of Travel and Tourism. ''It will be the overall shift. It has to."
Russell Nichols can be reached at rnichols@globe.com. 
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