On a sunny Friday in October, the Museum of the City of New York is buzzing. The hum of activity is interrupted occasionally by the crashing sounds of construction. Parts of the building—a handsome Georgian Revival structure on upper Fifth Avenue, built of brick and limestone in 1932—are closed to the public, as a renovation campaign enters its final phase. But the sunny galleries on the first and second floors still offer visitors fascinating displays of objects and images.

Upstairs a lively video surveys the whole history of New York City with well-chosen images and a lucid text. Camillo Vergara's photographs of the World Trade Center treat its two ungainly towers as jewels that must be seen from every angle—or at least from a Newark skyscraper, a boat yard on the Hudson, and a tenement block in the Bronx. They find the beauty in buildings that the photographer himself had disliked at first as grandiose and imperialistic. Period rooms, set in eras from the Dutch colonial period to the early 20th century, recreate the development of New York style.

Downstairs, a beautifully decorated corridor sets off a review of Cecil Beaton's career in the city. Photographs, high-concept magazines that make the sets and layouts of Mad Men look dull, and sumptuous opera costumes trace the British photographer's career in New York. The show illuminates his role, a big one, in the brilliant mid-century musical theater and ballet worlds—and includes the notorious note about New York's "Kikes" that could have derailed his progress (it didn't, a fascinating story in itself).

Other rooms display the development of the colonial revival style of the early 20th century (to which the museum itself belongs) and the impact of Kevin Roche's architecture on the city's skyline, street scenes, and Central Park. The marvelously detailed Stettheimer Doll House, which has fascinated New York children for decades, is still on display. But the museum, once known especially for its collections of historic toys, now offers a panoramic introduction to many of New York's worlds.

I'm here to interview an early-career historian—a recent PhD who turned down a long-term appointment in an Ivy League writing program to take a two-year fellowship in public history at the museum, funded by the Andrew W. Mellon Foundation (there is another fellow as well, a historian of architecture). In some ways, her job couldn't be more different from a normal teaching postdoc or beginning assistant professorship. She's working on two shows that will open in the spring: one on the world's fairs of the 1930s and a new one, "Capital of Capital," that will deal with the history of banking and finance in the city.

Early career historians in teaching positions usually do the bulk of their work—preparing lectures and classes, grading papers, keeping up with research—on their own. Public historians, by contrast, collaborate, with professionals in many fields, with administrators, and even with donors. The show on the World's Fairs will include parts of an exhibition from the National Building Museum, Designing Tomorrow: America's World's Fairs of the 1930s. But the Museum of the City of New York has its own unique holdings of everything from Raymond Loewy's designs for the streamlined buses that would transport visitors around the fairgrounds to scarves and other original memorabilia, and friends of the museum who collect art also own, and may be willing to lend, spectacular objects and images.

All of this makes up one huge Rubik's cube, and it takes a team to solve the puzzle. A designer will lay out the space for the show, establishing the number and the size of walls, cases, and platforms to be used—and setting an absolute limit on the number and size of objects to be shown. Research assistants will ransack the museum's collections, and those of other historical collections in the area, for the most striking items. The museum's director and other staff members—and the museum's board—will review the plans and make suggestions. Every model bus or building and every photograph that may be used has to be captured by digital photography, measured, and entered into a data base to which all the collaborators have access.

Ideally, every object should do at least two jobs: arrest the attention of viewers and tell part of a larger historical story. Making the final selection is brutal—the public historian's equivalent of killing one's darlings as one edits one's own work. So is writing the wall captions, which have to be masterpieces of compression without losing clarity or lapsing into the pretentious Voice of Time style that is as easy to parody as it is hard to avoid. And it all has to be done far enough in advance—ideally at least six months—that the museum staff has time to request the objects that have to be borrowed, to fabricate new cases where needed, and to prepare the whole range of wall texts, brochures, and digital materials that will accompany the exhibit. For the public historian, deadlines are deadly real.

Though only a temporary member of the museum's staff, the historian is acting as local curator of the show on the World's Fairs exhibit—and getting a fast and intensive course in many different skills. And that's only one of her jobs. For Capital of Capital, the museum has engaged a guest curator, Brian Murphy of Baruch College, and assembled an advisory committee. Murphy, who worked as a financial journalist before he entered graduate school, has chosen themes and laid out objectives for the show. In this case, since there's no existing exhibition to build on, everything from research through discussions with designers and administration to the final, case-by-case planning has to be done by early next year.

For this second show, the historian acts—in her own words—as "mission control," working with everyone involved to pull together what must sometimes feel like a squirming mass of loose ends. The nature of the process, moreover, means that new possibilities continually arise. As researchers look for illustrations of the exhibit's themes, they uncover materials that suggest new possibilities. The same happens, of course, as curator, designers and advisers discuss what the final show should look like. Traditional academic research is not wholly dissimilar: archival documents qualify the theses with which one starts out, and teachers and referees suggest changes of emphasis and interpretation as one writes. But there are many more cooks in this kitchen.

Though the exhibit will concentrate on earlier periods, it will also have an eye on current controversies. One thing a show like this can make clear is that many of the issues that dominate the newspapers today aren't new. It's not that presentist considerations dominate the presentation of the past—but that as historical scholarship reveals, anti-bank sentiment and horror and anger at speculation are hardly new to America, or to New York.

The job seems to be as exciting as it is demanding. Working conditions in the museum are conducive to constant collaboration. Though the two fellows have just arrived, everyone knows them by name, and experienced staffers appear not just willing, but delighted, to help and advise them. For a historian who has worked mostly with documents, photographs, and oral testimony, it's a constant pleasure to learn the multiple ways in which objects can tell stories: "I love," she says at one point, "working with stuff."

As we go behind the scenes, the complexity and range of the job become clearer. Deep in the basement, newly climate-controlled rooms house compact shelving full of photographs and works on paper, arrayed in their hundreds and thousands. The subject categories on the stacks—"Yiddish Posters"; "Brooklyn Newspapers"; "Minstrels"—suggest the vast range of the museum's holdings and the many ways in which they can be used to tell New York's stories.

For all its dedication to the allure and the power of originals, the museum is also deeply engaged in projects to make its materials available on the World Wide Web. In a neat, high-tech studio, street scene photographs taken on glass plates by Irving Underhill are being digitized. These slow-food pictures, as complicated and foreign-looking as Ben Katchor's graphic novels of a lost New York, contain a vast amount of visual information—far more than anyone can see just by looking at the originals. The digital images can be enlarged until they yield everything from the prices of cigars in a shop window to the name, on a floor high above the cigar store, of a detective who specialized in "Domestic Surveillance." As they go up on the web site, to join the 60,000 or so that are already there, they make the museum a window through which the world can look at New York's pasts. In the near future, every material show will have a sophisticated digital counterpart.

This is serious history. It's deeply informed by scholarship. And if it's well done, it will reach an enormous audience. Before renovation began, the museum attracted almost a quarter of a million visitors a year. As other floors open, more of the permanent collections become visible again, and these great New York shows open, they'll be back, and tens of thousands more will visit the museum virtually. This is a vital area of historical practice—and the museum is now seeking a second round of applications for its Andrew W. Mellon Postdoctoral Curatorial Fellowship. Let's hope more institutions find ways to give early-career scholars a taste of public history before they decide how they will spend—or divide—the rest of their working lives.

Anthony Grafton (Princeton Univ.) is the president of the AHA.