PHILADELPHIA — The Barnes Foundation’s move from suburban Philadelphia to the center of the city caused art lovers lots of worry.


Devotees of this great polyglot collection, heavy with Renoir, Cézanne and Matisse, which the omnivore art shopper Albert C. Barnes amassed between 1912 and his death in 1951, were appalled by the idea. Barnes spent years obsessively arranging his installation cheek-by-jowl in the mansion in Lower Merion, Pa., that he built for the purpose and opened in 1925, and he stipulated that, after he died, it should remain exactly as it was.


In 2002 the foundation’s board — constrained by limits on attendance and public hours imposed by zoning restrictions — announced plans to relocate. Many people, including a group that sued to stop the move, were sure that it could only desecrate this singular institution.


Others, myself included, did not object to the move per se, but felt that faithfully reproducing the old Barnes in the new space, as promised by the trustees, was a terrible idea. To us it seemed time to at least loosen up Barnes’s straitjacketed displays, wonderful as they often were. And why go to the trouble of moving the collection to a more accessible location when the galleries were not going to be any bigger?


And yet the new Barnes proves all of us wrong. Against all odds, the museum that opens to the public on Saturday is still very much the old Barnes, only better.


It is easier to get to, more comfortable and user-friendly, and, above all, blessed with state-of-the-art lighting that makes the collection much, much easier to see. And Barnes’s exuberant vision of art as a relatively egalitarian aggregate of the fine, the decorative and the functional comes across more clearly, justifying its perpetuation with a new force.


As a result, his quirky institution is suddenly on the verge of becoming the prominent and influential national treasure that it has long deserved to be. It is also positioned to make an important contribution to the way we look at and think about art.


Tod Williams Billie Tsien Architects, who pulled off this feat — and somehow managed to avoid the feeling of plastic fakeness that Barnes purists and Barnes skeptics alike were anticipating — deserves our gratitude. The Merion building and its 24 galleries, and Barnes’s arrangements within them, have been recreated with amazing fidelity in terms of proportions, window placement and finishings, albeit in a slightly more modern style. The structure is oriented to the south, exactly as in Merion; the same mustard-colored burlap covers the walls; the same plain wood molding outlines doors and baseboards.


As for Barnes’s arrangements, almost nothing is out of place: not one of the hundreds of great French paintings, none of the pieces of Americana, nor any of the Greek or African sculptures, the small New Mexican wood-panel santos or the scores of wrought-iron hinges, locks, door handles and whatnot that dot the interstices like unusually tangible bits of wallpaper pattern, often subtly reiterating the compositions of the paintings.


The only change to the installation — a big improvement — is the removal of the colorful fantasy of nudes in a landscape that is Matisse’s great Fauve masterpiece, “Joie de Vivre,” from its humiliating position on the stairway landing to a large alcove on the balcony overlooking the main gallery.


At the same time, some major systemic improvements make everything breathe in a new way. Especially important is the lighting system, designed by Paul Marantz, which seamlessly mixes natural and artificial illumination into a diffuse, even light, and had early visitors asking if some of the paintings had been cleaned. (They hadn’t.) There is also the spatial largess: The recreated building is set within a larger structure that includes a raft of amenities, among them a cafe, an auditorium and a gracious garden court with lots of padded benches, as well as a 5,000-square-foot temporary exhibition gallery that pulses with curatorial possibility.


Barnes’s arrangements are as eye-opening, intoxicating and, at times, maddening as ever, maybe more so. They mix major and minor in relentlessly symmetrical patchworks that argue at once for the idea of artistic genius and the pervasiveness of talent. Nearly every room is an exhibition unto itself — a kind of art wunderkammer, or cabinet of curiosities — where you can spend hours parsing the echoes and divergences among the works in terms of color, composition, theme, surface and light.