The wraps are starting to come off 2 Columbus Circle, which will be reborn this fall as the Museum of Art and Design. Although it remains within the dimensions and footprint of the original, the structure, formerly home to the Huntington Hartford Museum, has been fundamentally changed inside and out — and the city is much the poorer for that.

Since its inauguration in 1964, this beleaguered building has been one of the most enduringly divisive structures in the city, if not the world. No sooner had it opened than the architecture critic Ada Louise Huxtable dubbed it the “Venetian lollipop” building, because of the peculiar arcade at its base. And in the nearly half-century since, that label has stuck, like obscene graffiti smeared across its entrance — to be distinguished, naturally, from the actual graffiti smeared across its entrance. For the longest time, simply to mention “the lollipop building” passed for taste and discernment in matters of architecture and design.

Why did “everyone” hate this building, the loving labor of Edward Durrell Stone, one of America’s most eminent Modernist architects? Back in 1964, its tentative embrace of historicism, contextualism, and even irony — qualities later embraced by the Postmodernists — seemed heretical and appalling. It felt like decades since anyone had had the gall and poor judgment to attempt something other than a glass and steel curtain wall.

Often overlooked, however, is that even back then there were people who quite liked the building. Even if its embrace of Venetian and Byzantine motifs was halfhearted at best, still there was a positive enchantment to the place, a sense — and here I draw upon memories from my own childhood — that architecture could open up whole new worlds to the receptive soul. Unlike most buildings in Manhattan, 2 Columbus Circle presented a smooth, windowless expanse of gleaming white marble, qualified by adorable round portholes along the sides and ruddy granite accents. Imagine a Modernist re-enactment of a Venetian palazzo dropped into one of the busiest intersections in the busiest city in the world and encircled, like an island, by the ceaseless flow of traffic rather than the green waters of the Grand Canal!

But so entrenched was the antagonism to Stone’s building that, even after Postmodernism had incorporated many of its lessons into the emerging architectural consensus, people still hated it, even if they had forgotten why. Thus, when 2 Columbus Circle was offered to several New York cultural organizations a few years back, having been all but abandoned for a generation, the Landmarks Preservation Commission refused even to debate its destiny. Nor did it help that the architect of the renovation, Brad Cloepfil, was dismissive of the building itself and of the concerns of many eminent architects and historians: “It’s far too weak of a piece of architecture for that site. That site deserves and demands more.” As for his critics, he referred to them in the spring 2005 issue of Bomb magazine as “a very small, exclusive and elitist group that opposes most Upper West Side development.”

Given such talk, one would have expected something brilliant from Mr. Cloepfil or, at the very least, something boldly, memorably bad, a defiant stunt of landmark proportions. And yet the new façade is so mind-numbingly dull as to lack even the posture of ambition. In place of Huntington Hartford’s Venetian reverie we have a structure that would not look out of place as an annex to a suburban outpatient center. The brilliant white marble is gone, together with the portals, and in their place Mr. Cloepfil has come up with a flattened, vaguely asymmetrical mess of off-white, sallow, and pale gray panels that lack any formal, cultural, or contextual resonance or coherence. Can this possibly be the “more” that “the site deserves and demands”?

While every completed building looks better than it looked under construction, it defeats my powers of imagination to conceive how the Museum of Art and Design will ever look much better than it does today. Surely there can be no reasonable doubt that the interior of Stone’s building was cramped and impractical. It should also be said that the delightful auditorium in the basement, with its plush red velvet seats, has survived the transformation. But a major objection to the first building — that it was largely windowless — has not been effectively addressed: There are more windows than before, though the glass is mainly tinted and the new façade is mostly occluded with tiles.

Say what you want about Stone’s building, it was indubitably a landmark; the best that can be said for its replacement is that, if we’re lucky, no one will ever notice it. That timid banality, that sense of fading into the woodwork and ducking for cover, has been the defining spirit of New York architecture since the 1970s. It is true even today, when architects are allowed somewhat freer rein than in the past, so in one respect, at least, Mr. Cloepfil’s design will not disappoint.

A thought occurs that might help us out of our newfangled mess: Assuming that what was done to the interior is what needed to be done all along, it might be relatively easy — not now of course, but after a decent interval of, say, five years — to restore the original façade. In the meantime, might I suggest to the new tenants that they needn’t feel any rush to take down the remaining tarps that cover Mr. Cloepfil’s building.