For nearly a century and a half, the Metropolitan Museum of Art, the beaux arts behemoth on Manhattan’s Upper East Side, has been rather a dowdy operation, a standard-bearer for everything ancient and ageless in human culture. Now, quite abruptly, it’s on the move: First stop, Madison Avenue and 75th Street, where the former home of the Whitney Museum of American Art has recently reopened under the banner of the Met Breuer, with new exhibitions and a new curatorial outlook that could reshape the public profile of the largest art museum in the Western Hemisphere.

The change has been in the making since at least 2008, when the museum board selected Thomas P. Campbell as the Met’s new director and CEO. His predecessor, the courtly Frenchman Philippe de Montebello, presided over the museum for three decades. Hardly a caretaker director—the Met doubled its exhibition space under his watch—de Montebello favored a mostly hands-off approach to the museum’s assorted departments, letting the ivy grow, curatorially speaking. Susan Sellers, who was hired by Campbell in 2013 as the head of a newly reinvigorated department of design, described de Montebello’s Met as being “like a university,” a gaggle of somewhat disjointed faculties. Sellers’s job is part of Campbell’s new direction, an attempt to bring a consistent visual identity to the museum’s disparate parts—including the Met Breuer, five blocks down and one block over from the Fifth Avenue mothership.

It may seem an odd paradox that the Met is simultaneously unifying its structure and broadening its reach, but that’s precisely what’s happening. The move into the Met Breuer—renamed for its architect, Marcel Breuer, after the Whitney decamped for its new Renzo Piano–designed digs in the Meatpacking District—was arranged in part to accommodate a massive trove of modern art donated to the Met by cosmetics magnate Leonard Lauder. The modernist ambition of the Metropolitan Museum of Art has lagged behind the Whitney, the Museum of Modern Art, and the Guggenheim for much of the last century. The $1.1 billion Lauder gift instantly made the Met into a prime destination for twentieth-century paintings and sculpture—it includes 33 Picassos and a smattering of works from Fernand Léger, Georges Braque, and Juan Gris. Managing the newly acquired horde is Sheena Wagstaff, installed in 2012 as the first curator of Campbell’s department of modern and contemporary art. No longer just a storehouse for Greco-Roman artifacts and impressionist blue-chip paintings, the Met is now a serious contender in the fast-paced modernist marketplace.

It even has the modernist monument to prove it. Marcel Breuer’s building opened in 1966 to mixed reviews. Breuer himself saw the museum as an antidote to Madison Avenue’s skyscrapers and its art as a bulwark against the ad men within. In his notes, Breuer wrote of his building: “It should transform the vitality of the street into the sincerity and profundity of art.” A lumbering, top-heavy exercise in quasi-Brutalism, it was not a building that played nicely with its Upper East Side neighbors, who were slow to accept a parvenu in their midst. Once they did, however, their embrace was total, and by the late 1970s the Whitney’s plans to expand the building were repeatedly thwarted by ear-piercing hues and cries about the potential damage to the beloved local landmark. A 1985 scheme hatched by Whitney director Thomas N. Armstrong III would have expanded the footprint by demolishing neighboring brownstones and using the current museum as a building block for an enormous addition by Michael Graves. The plan went through years of review and almost sparked a civil war among the museum’s board members before it was shelved. The decision to move the Whitney to the foot of the High Line was a direct outgrowth of the near-fanatical devotion to Breuer’s original vision.

Restoring that vision to its bygone glory has been the objective the Met and its architects, Beyer Blinder Belle, have pursued at double speed during the 17 months between the Whitney’s departure and the debut of the rechristened Breuer. The building’s lobby, with its bush-hammered concrete walls and smooth concrete trim, has been beautifully refurbished, the stains and patches of 50 years artfully blended and blasted away; the lower-level courtyard has been replanted with slender aspens, making it feel more like a sylvan hideaway instead of the dreary narrow well it had become.

The bookstore that once occupied a fair chunk of the northern side of the ground floor has been removed, leaving an open space topped by row upon row of now-iconic round pendant lamps, cleaned and fitted with working lightbulbs of consistent color and luminosity. Ever since their acclaimed work on Grand Central Terminal in the early 1990’s, Beyer Blinder Belle has held an almost undisputed claim to the mantle of New York’s finest and most sensitive architectural fix-it men. They haven’t flagged here, an especially impressive accomplishment given what must have been a considerable temptation to improve on Breuer’s sometimes ungainly design. The 29,000 square feet of exhibition space, modest by contemporary standards, is spread across four stories of bluestone and parquet floors. It’s all still there: the irregular trapezoidal windows, the darkened staircases, the openwork cement drop ceiling, the visible ducts, the gangplank entryway spanning the sunken court like the drawbridge to some surreal castle. If anyone was worried the repurposed building was going to lose its edge, they can rest assured the Met Breuer is still very much the weird old Whitney. When Ada Louise Huxtable reviewed the building in The New York Times in 1966, she grudgingly admitted its pleasures: The taste for its disconcertingly top-heavy, inverted pyramidal mass grows on one slowly, like a taste for olives or warm beer.”

In tandem with the new space, the Met revealed a redesigned logo in February—a white background punched with the words THE MET stacked one on top of the other in red—only to have the Wolff Olins–designed emblem greeted with a torrent of online abuse. New York magazine’s Justin Davidson compared it to a bus crash, another online wag summed it up with two other piggybacked words: THIS SUCKS. In truth, the new logo doesn’t look half bad waving from the flagpoles of Madison Avenue, but the best that can be said of it is that it looks like it belongs on the shopping bag of a very fine department store in Indianapolis, during the heady early days of the Carter Administration.

Sheena Wagstaff, chairman of the department of modern and contemporary art.Damon Winter/The New York Times/Redux

More serious errors are evident within the Breuer. It may be merely a case of shaking the bugs out, but the restoration has thus far excluded such details as the bronze fixtures on the doors to the bathrooms and service areas, which are still oddly skewed and unpolished, sometimes smeared with white from a recent, or possibly decades-old, paint job. A number of observers have noted the removal of the custom granite shelving at the rear of the lobby, replaced by a large digital display advertising the current exhibitions, though the Met has reassured the preservation-minded public that the wall is extant behind the screens. The museum has yet to account, however, for the large, visible rips in the insulation over its famously visible ductwork, which is certainly a pressing functional as well as aesthetic concern. And then there’s the strangely spotty and unprofessional treatment of the foot of the temporary exhibition walls, below which still more white paint splotches are visible on the wooden floors, a carelessness that would be unacceptable at the Met’s Fifth Avenue location.

These rough-and-ready fine points make an intriguing, if almost certainly coincidental, counterpart to the large inaugural show on the museum’s upper floors. Unfinished: Thoughts Left Visible is a survey of incompletion through the ages, with portraits and landscapes from Titian through Elizabeth Peyton in various states of imperfection. As high-concept exhibitions go, this one doesn’t exactly belong in the uppermost intellectual stratum, but it works, and visitors can spend hours examining the minutest pentimenti of the greats and wondering what might have filled the blanker segments of the canvases. More importantly, the show affords a convenient device for cutting into a deep core sample of the Met’s collection—featuring, of course, some of the recent Lauder contributions—and demonstrating how the Breuer might work as an instrument for revealing correspondences and narratives that run from the Renaissance straight through modernity. Incompletion itself, one might say, is the essence of the Met in its current moment of transition.

Latter-day developments are on full display on the second floor, where Indian modernist Nasreen Mohamedi gets a full retrospective of her exquisitely hand-hewn line drawings. Lined up to succeed her are photographer Diane Arbus and painter Kerry James Marshall—the latter of whom was on hand during the press opening in early March, and who reflected on the peculiar privilege of finding himself, at 60, suddenly under the same institutional penumbra as some of history’s most lauded artists. “In a lot of ways, we”—the living, the insurgent, the un-lionized—“want to be a part of that club,” he said.

It’s a fitting future for a building that, under the Whitney’s stewardship, always managed to feel a little inchoate and eerie, a looming architectural question mark that hosted some of the most influential shows of the last half-century: In 1991 alone, the Whitney biennial—an art-world mainstay since 1932—helped introduce the world to artists as varied as Eric Fischl, Cady Noland, and Felix Gonzalez-Torres. But it poses a different kind of question for the Met, which risks not so much a dilution of its brand as a worrisome case of mission creep: If the museum’s mandate is to expand into the commercial realm of modern and contemporary art, will the institution lose some of its high-minded luster?

The entire Breuer initiative has been a family affair, arranged by Lauder, who also made a $131 million donation to the Whitney in 2008 to ensure that the building wasn’t sold. The Met then stepped in to sign an eight-year lease, relieving the Whitney of the associated costs. The last time the Met opened a satellite location, it was also the work of a single family, the Rockefellers, who in 1924 gifted their substantial holdings of Gothic and Romanesque art and then gave away a chunk of land on which to build the Cloisters. Unlike Lauder, the Rockefellers were not major players in a white-hot art scene that has seen the world’s wealthy turn to auctioneers, gallerists, and private dealers as de facto bagmen for converting cash into portable artistic investment vehicles. The Met is now positioned very close indeed to this churning economic whirlpool.

However, the Met has been here before—a moment when it not only survived but prevailed. In the 1960s, the enterprising curator Henry Geldzahler launched the first contemporary exhibitions at the Met and proved the museum could be both canonizing and progressive by bringing in new voices—Andy Warhol, David Hockney, Robert Rauschenberg, James Rosenquist, Adolph Gottlieb—who would become, just as Kerry James Marshall hoped, part of the club. But while membership has its privileges, there are also dues to be paid, and a new building does not make an institution. The Whitney, smaller and more nimble, charged with an experimental sensibility that it sees as intrinsically American, was perhaps better able to produce shows of greater originality and freshness during its Madison Avenue residency than the slower, larger Met can hope to do in the same setting. And if the Met, with all its historical baggage tries too hard to be the Whitney, the results could be awkward.

The architect Rem Koolhaas—who, incidentally, was tapped for a scuttled revamp of the Breuer in the 2000s—recently made the provocative suggestion that some contemporary buildings could be preemptively landmarked; a process of instant canonization, history catching up with the present. If the Met Breuer is poised to do the same thing to contemporary art, emblazoning it with THE MET and all that that portends, it might produce a compelling and salutary challenge to the whole idea of the canon itself; but it might also entail a peculiar, and uncomfortable denaturing of the Met’s cultural role.