There was a time, within living memory, when Midtown was a name to conjure with. From D-Day to the fall of Saigon, this patch of Manhattan stood for Modernity itself, Modernity made visible in the curtain walls of Union Carbide, the stainless-steel cladding of Socony-Vacuum, and the reflecting pools of the Seagram Building.

For no very good reason, every other movie of that era seemed to take place in the implacable grid that stretched from 42nd Street to Central Park and from Times Square to Second Avenue. Even if nothing in the plotline required Doris Day and Rock Hudson to work and mate in the high-rises of Midtown, a reason could always be cooked up to justify using, yet again, this most compelling visual backdrop of the atomic age.

How times have changed! The camera crews – obedient as always to shifting tastes – are back in Manhattan, but anywhere other than Midtown. They have taken to haunting such newly picturesque areas as the Upper West Side, TriBeCa, and the East Village.

The reason is not hard to find. We have grown weary of Modernity, and so we are charmed by everything that is not Modernity, everything that is small and human-scaled and that betrays the grace of age. Furthermore, tall buildings are no big deal these days. Every city has them, and most of them are better than most of ours.

Even a revival of the Modernist vocabulary in recent architecture has done nothing to resuscitate Midtown as an idea. For the reality of Midtown never rivaled the hype: The practice almost always betrayed the principle. Midtown grew, as forests grow, one building and one tree at a time, with no thought to the beauty of the whole or even the part.

When the process was over, it was not the monumental Empire State and Chrysler Buildings that carried the day, but the disgusting, impersonal, oversized cabinets of Emery Roth & Sons, 60 of them to be exact. It was a heritage so banal that this firm, which once graced us with the San Remo and the Beresford on Central Park West, now disclaimed even the intention of cranking out anything other than rentable, pre-packaged office space that wouldn’t collapse under you.

The remarkable thing is that, without being especially good, the architecture in Midtown has been improving in recent years. The purely utilitarian nature of Midtown architecture has changed only to the extent that now some show of effort, more than the effort itself, is required to appease into silence an uncritical public. But most of the newer buildings at least aspire to create some individuality and formal interest.

Think of the Lipstick and AT&T Building by Philip Johnson or Fox and Fowles’s Reuters and Conde Nast Buildings in Times Square. The staggered terraces of Der Scutt’s Trump Tower and the perspectival gimmicks of Metropolitan Tower, next to Carnegie Hall, repay the attention of pedestrians, while the new 360 Madison Avenue, by Richard Cook, is as distinguished as they come.

But for all that, Midtown no longer means much to New Yorkers. With the exception of tourists who do what their guidebooks tell them, it is unlikely that anyone visits this part of the city, as New Yorkers themselves once did, to experience Midtown itself. It has been reduced to a series of mostly forgettable buildings where many of us work and some few of us live.

What was it that doomed Midtown as a place of collective sentiment? Perhaps it will help, here as well, to conceive Midtown in cinematic terms. By the 1930s,it already seemed to be the objectification of those myriad dream-towers that Fritz Lang, himself inspired by the New York skyline, had created out of pasteboard as the back-drop for his Expressionist masterpiece, “Metropolis.”

But Midtown, in turn, was itself like pasteboard to this degree – that, especially after World War II, it became a composite of pallid and neutered architectural acts, executed swiftly and on the cheap, that were almost suffocating in their soulless conformity. The pedestrian was not meant, he was not expected, even to look at these buildings as individual acts. They were to be an architectonic projection of what he himself was supposed to be, but was not: the Organization Man, infinitely reproducible, infinitely replaceable.

Aside from its utilitarian functions, which it served adequately enough, Midtown was supposed to blur into a grandiose and none too specific composite of power, wealth, and modernity. What happened, however, was that the moment came when the Man in the Gray Flannel Suit looked up and discovered that he was living in a world of inexcusable ugliness. And he began – in slow motion, perhaps, but with mounting indignation – to rebel against the architectural circumstances in which he was made to work.

So when did the tipping point occur? In her recent distinguished work of architectural history, “Pan Am and the Shattering of the Modernist Dream” (MIT Press), Meredith Clausen suggests that it was the Pan Am Building that marked the transformation from the mythic Midtown of the post-War years to the urban armpit that we know today.

If Walter Gropius’s slab had simply been, as it was, a big, ugly Modernist mistake, it would not have carried the wallop that it did. But inherent in the Pan Am Building’s very conception was one element that propelled it to an exponentially higher orbit of obnoxiousness. Whereas all previous New York skyscrapers had had the decency to remain within the street grid, the Pan Am straddled Park, one of the fairest avenues in the city, in such a way that it permanently marred and plugged that peerless corridor.

Forty years on, the building remains, even though Pan American Airlines has faded into history. Now going by the name of Met Life, the building has the aspect of a gravestone: Beneath it lie buried the myths of Midtown and of Modernity itself, as they occupied the popular imagination nearly half a century ago.