It's a sunny day in mid-May and Kevin Walsh is standing on a corner of City Island, surrounded by 30 people with tote bags and cameras. Walsh is about to embark on his latest "Forgotten New York" tour, an occasional outing in which he leads trips to lesser-visited aspects of the city. Before he even has a chance to speak, they're clicking away, anxious to get everything they can on film. After all, City Island, which lies off the east coast of the Bronx, is picturesque enough to pass for a New England fishing village.

But despite their multiple cameras and slightly befuddled faces, these aren't tourists, at least not the just-off-the-bus-from-Toledo type. They're New Yorkers, fans of Walsh's Forgotten New York, one of the best websites for New York history. And they've come to watch Walsh, who researches, writes and designs the site, in action.

In a field with no shortage of hobbyists and cranks, Walsh stands out as both an authority and an innovator. There are lots of sites devoted to New York's trains, neighborhoods and even broken doorknobs, but Forgotten New York is the only one to bring it all together, with pages on everything from Manhattan's last primeval forest (in Inwood Hill Park) to the evolution of street names in Astoria. Walsh, 44, who makes a living as a copywriter for Macy's, adds a page to the site about every other week. More than a blog, the entries are thoroughly researched and referenced, with period and contemporary photographs and maps.

Born and raised in Brooklyn, Walsh is stocky and goateed, with a thick Long Island brogue and the attitude that usually comes with it. "There are several places I wanna see, and you're coming along," he tells the group.

At the same time, Walsh defies many of the New York stereotypes. He's often quiet and introspective. As Sharon Seitz, co-author of "The Other Islands of New York City," said, "he's not loud about [his work]. He's not really very talkative." And Seitz praised Walsh for defying another New York stereotype: While many tour guides are in it for the money, Walsh is driven solely by his "love for the city and its many layers of history."

True to form, Walsh's tours, which he gives for free once every few months, are less of the "follow the leader" than the "come explore with me" school. Walsh says that he has only a few regulars on his tours, but most of the participants are budding urban geography experts themselves, and the City Island tour group was abuzz with the shoptalk of urban arcana. A Forgotten tour may be one the few settings where you can hear people heatedly debating the best intersections in Brooklyn, or the merits of different makes of subway cars. As the tour meandered across City Island Avenue, one teenage boy in the group pointed at a Victorian-era house and said, "check out the honeycomb roof shingles."

Walsh is far from alone in leading amateur tours. Seitz, who with her husband Stuart Miller recently wrote the third edition of the "Blue Guide New York," said she has noticed an increased interest in the New York outside of Manhattan in recent years, something she attributed to the general upswing in the city's economy over the last 10 years. "I look in the Times on Fridays, and every week there seems to be more of these walking tours."

Indeed, the Forgotten tours are only one of many offered in the New York region. There areoutings on everything from factories in Queens to abandoned mental hospitals in Connecticut, and they range from individual projects like Walsh's to institutions like the Brooklyn Center for the Urban Environment. Many of the people on the City Island tour, in fact, have aspirations of conducting their own urban adventures — one middle-aged man talks of plans to circumambulate Brooklyn.

Walsh, though, is not satisfied with his amateur status. While he has no training in archival research or history (he has a bachelor's in sociology from St. Francis College), he said in an interview that he'd like to make a career of his historical work — his ideas include a book and a series of "Forgotten" programs in cities across the country.

But his ultimate goal is something a bit higher still: to change the way New York sees itself, its history and its environment. Like Jane Jacobs, the Greenwich Village intellectual who championed street-corner shops and sidewalk life in the 1960s, Walsh sees a New York City again intent on development at the expense of its present and past. "Any preservationist momentum in NYC has always come from the grassroots," he said. "New York City, in its official capacity, has always been about tearing down the old stuff and putting up newer, taller, better 'new' stuff. Look at Times Square..."

For Walsh, the not-so-hidden agenda behind Forgotten New York and the Forgotten tours is to promote a different kind of tourism, one that values the city not for its looming landmarks but for everything else. "I can't tell you how frustrating it is for me to pick up typical New York City guidebooks and see 200 pages on the usual suspects in Manhattan, and 25 pages on the 'other' four boroughs," he said. "Or pick up New York Magazine and see how the world revolves around a small coterie of rich twits in midtown Manhattan. Then I go to Maspeth, Inwood or Stapleton or Brighton Beach and photograph the real New York City and the buildings, ads or other structures from decades past; these, and the people that made them and the people that reside next to them, are the real New York."

Walsh grew up in Bay Ridge, Brooklyn, about as "real New York" as one can get. He said he remembers as a child going on bus trips with his mother and being fascinated with the intricate streetlights that graced the major streets. "I would make up my own lamppost miniatures using a pencil, spoon and flashlight bulb," he said. "I would dig in the dirt, smoothing out the ground to make my own roads." During the 1960s, though, these were replaced by ugly, utilitarian upgrades, with only a few "forgotten" poles dotting the cityscape (Indeed, lamppost "necrology," as Walsh calls it, plays a major part in the Forgotten web site.)

Walsh also grew up in close proximity to the Verrazano Bridge — or, at the time, the lengthy preparations to build what would become the world's highest suspension bridge (that's him at the top of the page, in 1963). "I watched them build the thing," he said. "Anyone watching the bridge being built can't have helped but be influenced in some way."

Though he's since moved to Queens, Walsh has kept in touch with his childhood fervor for the unseen parts of the city. The Forgotten website is packed with information, clearly organized but overwhelming all the same. Neal DeMause, the editor of Here Magazine and a frequent Forgotten tour participant, compares his work to that of such New York academic historians as Luc Sante, whose 1992 book "Low Life" delved into the lesser-known, less glamorous aspects of lower Manhattan's past. "I think [Walsh] has done an incredible job of digging up fascinating stuff, the New York history that doesn't get featured on PBS specials," Demause said.

Walsh first began researching and taking pictures for Forgotten in 1998, but he said he waited until he had a few dozen pages worth of material before launching the site, which went live in March 1999. Walsh has kept up a fairly regular updating schedule, with new material coming either from tours or his own research, which often comes from long walks in the far corners of southeast Brooklyn or North Bronx. One recent entry focused on an abandoned farmhouse on Staten Island, another on an obscure rail junction.

Since the launch, Walsh has garnered a sizable cult following, and his site is a sort of "all roads lead to" destination for the New York urban-exploration set. It's been mentioned in Salon, as well as many of the local papers. Fast becoming an authority on an aspect of New York most residents never think about but, when prodded, find infinitely intriguing, Walsh may soon see his exposure grow wider still. The next few years will see the debate over lower Manhattan reconstruction go into overdrive, while the Bloomberg administration tries to negotiate serious budget cuts while making desperately needed renovations to the city's infrastructure. Both will force a widespread discussion about the meaning of New York culture, and integral to that is the meaning of the city's past. Is it only the big buildings and notable landmarks, or is it also the period streetlamps and hundred-year-old signposts?

Mayor Bloomberg, so far, gets mixed marks from Walsh. Discussing the mayor's decision to renege on moving the Museum of the City of New York to the renovated Tweed Courthouse, he said, "I was disappointed to hear of Bloomberg's cancellation of the deal because it reveals his mindset. He believed that such a large space would be a waste of money if it were used as a museum and the public allowed to enter. So, he would rather fill it with his beloved cubicles and run the Board of Ed, or whatever succeeds it, from the Tweed."

Whether Walsh actually will be the next Jane Jacobs remains to be seen; for now, he keeps plugging at Forgotten New York, building an ever larger base of New York history. He says he has been in contact with publishers about a book project. "My goal is to become known," he says, "as NYC's foremost amateur historian." But, true to form, he quickly amends himself, adding, "I feel that now, even though Forgotten has been mentioned favorably in all of New York City's daily and weekly publications, I'm still a schmuck with a website. Until I am published, I can't call myself legitimate."

Clay Risen can be reached at risenc@yahoo.com.