Construction fences are coming down from around the dour travertine bulk of the Juilliard School at Lincoln Center, revealing the spacious new lobby of Alice Tully Hall through high walls of glass.

Last year’s crash may have halted a mighty transformation of the New York skyline, though Tully is among the welcome fruits of the boom that New York will enjoy in 2009 and beyond.

Pundits already have scribbled their obituaries for the past era’s architectural excesses. The Museum of Modern Art’s $858 million expansion in 2004 is usually deemed Exhibit A, though the Tokyo architect Yoshio Taniguchi serenely united its many moving parts without empty grandiosity. Underlying the criticism is a yearning for a more intimate MoMA and, by extension, for a less intimidating city. The museum’s vastly greater size and the millions who throng its halls are signs of success and dynamism we may soon deeply miss.

MoMA will age more gracefully than the decades-long remake of the Metropolitan Museum, overseen by Philippe de Montebello, who departed in 2008. The Greek and Roman galleries, reopened in 2007, are among the very few spaces that invitingly display the huge collections. I’m hoping this appeal extends to the renovated American Wing, which reopens this spring.

Most of New York’s most extravagant architectural ideas never got beyond breathtaking computer renderings. Thomas Krens exited the Guggenheim last year, having largely failed to extend the museum’s brand beyond the fronds of titanium and glass waving in Bilbao, Spain.

Instead we were treated to a tiresome debate about what color to paint Frank Lloyd Wright’s spiral on Fifth Avenue. Such small-bore battles too often consume this city, which is noisy with activists fearing the new. And, regrettably, the new too often deserves the hostility.

The city needs to fix a landmarks process that favors defacement, though the economic bust may save us from the pendulum swing to historic-preservation absolutism.

The Roaring Twenties left behind a soaring, stair-stepping skyline, decried at the time as vulgar. This boom decade leaves us with timid boxes skinned in murky gray glass: The Trump SoHo (by Handel Architects with the Rockwell Group), Slazer Enterprises’ 50-story One Madison Park and Extell Development’s Ariel East on the Upper West Side. (Condo design factory Cetra/Ruddy cranked out the latter two.) The art was in their cynical manipulation of the zoning code.

After Tully Hall, Lincoln Center will open an expanded and renovated Juilliard School and finish overhauling its 65th Street frontages and iconic plazas. It’s all the work of Diller Scofidio & Renfro, architects whose talents include navigating the center’s snake pit of competing egos and agendas.

Too bad Lincoln Center hasn’t been able to work similar miracles with the acoustically challenged Avery Fisher Hall. The New York State Theater, in the midst of technical and cosmetic fixes, will likely remain a hostile place to view performances by the struggling City Opera.

The Friends of the High Line, also with Diller Scofidio & Renfro, have steered an unloved 1.5 mile railroad roadbed into a lushly meadowed park that’s now almost complete — to amazingly little controversy.

Metal and glass condo towers muscled their way skyward in the traditional gold-coast districts, though they also popped up in numbing metal-and-glass uniformity in Long Island City and the Dumbo and Williamsburg sections of Brooklyn — neighborhoods once defined by aluminum-sided row houses and artist-ready industrial lofts.

Many city neighborhoods will benefit for years from long- overdue investments, both private and public. Broken-windowed yet sturdy brick apartment buildings in the Bronx found new life. Square miles of Brooklyn’s East New York, long left for dead, see kids playing in the streets again.

The most confident designs came late in the boom, and the length and depth of this downturn will determine their fate, like the shimmying silhouette of Herzog & de Meuron’s skyscraping Tribeca condo at 56 Leonard St. The same architects gave us street-scaled sensuality in the Coke-bottle-green glass columns of 40 Bond St.

Even if the real-estate market rapidly stabilizes, the crash may at last deep-six the notion that private development can finance costly public infrastructure. The $14 billion Penn Station fiasco has not been heard from since the Spitzer meltdown. Let’s administer the last rites and then begin begging President Obama for some of those economic-recovery billions to help build a proper train station — period.

Bury the Hudson Yards horror and forget about the tower design furtively unveiled last month to crown the Port Authority Bus Terminal. None of these will generate the touted infrastructure-subsidizing dollars, while making construction infinitely more complex.

These boondoggles, along with staggering ineptness at the Ground Zero site, were the boom era’s biggest failures.

New York has a storied history of erecting great public works when times were hard — from the Triboro Bridge to Riverside Park. Now we should prove we can still do it.

James S. Russell