New York got one of its beloved public spaces back. Credit Eric Hammarberg, an engineer at Wiss, Janney, Elstner Associates, for ensuring all that delicate, ornamental plaster on the decorated ceiling of the Rose Reading Room atop the 42nd Street library, which had begun collapsing, won’t fall down. And the former Whitney Museum of American Art on Madison Avenue, rechristened Met Breuer, was also restored. Beyer Blinder Belle, the New York architecture firm, performed an act of thoughtful and immaculate preservation. This once-reviled 1960s building, now with its patina of age, is finally coming to be recognized for what it is: a practical Modernist landmark of exceptional finesse and a surprisingly good neighbor.  The Roy and Diana Vagelos Education Center, devised by Diller Scofidio & Renfro (in collaboration with Gensler), is a whimsical 110,000-square-foot exclamation mark on Columbia University’s Upper Manhattan medical campus near the George Washington Bridge. The 14-story tower’s camera-ready face looks south. It presents a cheerfully teetering stack of cantilevered terraces, indoor bleacher seats, lounges and stairs. They spill toward a handsome wood-lined amphitheater linked by steps to the sloping sidewalk. One can picture a giant pinball bouncing from the top of Vagelos and rolling down Haven Avenue.  The architects call this sunny, wide-open south side the “study cascade.” Offices and classrooms fill the more conventional north half of the tower, which is clad in a fritted milky curtain wall that’s less striking outside but mitigates solar heat gain. State-of-the-art anatomy classrooms tucked behind the cascade are part of a deceptively pragmatic layout. A restrained palette — of white, orange and Douglas fir panels stained a burnt sienna — balances the sculptural gymnastics. The other day I found students poring over their laptops in the ground-floor lounge. Some grumbled a little about minor early-days stuff like not enough electrical outlets, but they all said they loved the architecture. I do, too. It’s what medical schools generally aren’t: playful, welcoming, warm. And when the sun sets, the center becomes a beacon in the neighborhood.  Farther south, Columbia’s 17-acre Manhattanville campus began to take shape this fall with the construction of an arts hub and completion of the Jerome L. Greene Science Center, an urbane glass-and-steel behemoth by Renzo Piano rising beside the aged No. 1 subway viaduct, near the intersection of Broadway and 125th Street.  The building is a nine-story, 450,000-square-foot nexus for neuroscience. Four steel-frame glass blocks surround a glassy core with meeting rooms. The basic shape is nothing pyrotechnic, but, as usual with Mr. Piano, the nub is in the details and in the light. A double-skin curtain wall, the two layers separated by a muffling pillow of air, lets light flood in while reducing the rumble of the elevated subway. I write these words inside another of Mr. Piano’s buildings, staring from a glass cubicle through several more layers of glass across a birch-filled courtyard. My colleagues across the court look almost immaterial. The Greene Center engineers even greater illusions of ethereal weightlessness, the layered glass membranes held in equilibrium by a clockwork of steel beams and cables, tinted powder blue. Like church spires, tall twin smokestacks announce the campus from afar, declaring the center a factory for ideas.  The industrial nostalgia recalls Mr. Piano’s ship-shaped new Whitney Museum and is clearly meant to substitute midcentury symbols of modern commerce for the usual classic emblems of institutional authority. A plaza stands in for the ancient agora. The center will anchor one side of the evolving Manhattanville project, with its multidisciplinary aspirations, underground passageways for Columbia people and variety of street-level public spaces. These are intended partly to appease angry former residents of the neighborhood troubled by Columbia’s gentrifying expansion, and also to signal that the university is opening itself up. Mr. Piano envisions a kind of Italian piazza, democratic and energized. We’ll see how further development follows through on that promise.  Several weekends this summer, I hopped the ferry with the family for Governors Island. Back in 2003, the federal government sold the island to the city, which got a derelict former military base that included some lovely historic officers’ homes. Leslie Koch was hired in 2006 as president of the Trust for Governors Island. She enlisted Adriaan Geuze of West 8, the landscape architecture firm. Ms. Koch and her team spent years just watching how people used the island, seeing what was wanted. They responded with food carts, mini-golf, Adirondack chairs, bike shares, children’s programs and art projects.  The last, most ambitious phase of redevelopment was completed this summer: man-made hills (cost: $71 million, half public, half private money). A hill with twisty slides for kids became an instant sensation; another features a sculpture by Rachel Whiteread. The tallest has a killer view of the Statue of Liberty and much of the skyline.  Mr. Geuze’s design for the island established a high-water mark for resilient planning, taking into account not just sea rise and storm surges but also social cohesion. Watch the mix of parents and children around the slides, sprinklers and food carts on a warm summer Saturday afternoon. Governors Island is New York as a diverse and joyful city. Mr. Geuze and Ms. Koch, who stepped down this year, deserve medals. Now City Hall has to find tenants to help pay for the island’s upkeep. Big office or apartment towers would undo much of what has been accomplished. Here’s hoping that some venturesome, well-endowed university or cultural institution is seeking a beautiful home.  Most rental apartment towers end up vanilla-brick or glass nonentities, invisible at best. Not Via 57 West. No building redrew the city’s western skyline more ingeniously than Bjarke Ingels’s first completed project in New York: a warped, mountainous pyramid hugging the Hudson River at 57th Street. Already filmmakers have exploited it in “Doctor Strange.”  The shape is not a pyramid, actually, but a hyperbolic paraboloid, rectangular on the ground, with a swooping roof-facade, a bit like the billowed sail of a ship, sweeping upward from 12th Avenue to the mast’s peak at the northeast corner of the site, 467 feet high. Looking from 11th Avenue and 58th Street, the 32-story building resembles a spire. From elsewhere, it unfurls, its saw-toothed balconies, angled toward the Hudson, making hundreds of facets in the stainless-steel skin, which shimmer with the changing light.  This is a building very much designed outside in, notwithstanding that the Danish Mr. Ingels has trumpeted the nice “Scandimerican” stylings of the lounges and handsome oak-and-brick lobby and the community-enhancing function of the landscaped private courtyard at Via 57, which recalls his design for the 8 House in Copenhagen. Sliced from the center of the building, the courtyard leads to riverfront terraces with outdoor grills and a host of indoor amenities. I’ll be curious to know how much this fosters community. The amenities require a fee. Twenty percent of the 709 apartments are set aside for subsidized tenants, in return for which the developer enjoyed the usual tax breaks. Otherwise, Via 57 seems to market itself toward brokers and Westchester doctors who can pay top dollar for the light but sometimes cramped apartments off double-loaded corridors, a hike from the nearest subway.  Of course, tenants are also paying for the pleasure and cachet of living in a striking work of architecture. New York’s former planning commissioner Amanda Burden deserves a shout-out here for pushing Douglas Durst, the developer, and Mr. Ingels to cook up something bold at such a conspicuous site. The three of them have given the city a new spectacle.  O.K., I get one Grinch moment, not about the $4 billion shopping mall attached to a PATH station at ground zero or the election of a president who, among other things, believes privatization is the answer to what ails the nation’s infrastructure.  No, I want to grouse about one of the sadder excuses for architecture completed this year. You can nominate your own candidate. This one is a kind of sleeper, at Mulry Square, at the intersection of Greenwich and Seventh Avenues, in Greenwich Village. There the Metropolitan Transportation Authority finished building a $180 million emergency ventilation plant. The site is opposite the new St. Vincent’s Triangle Park and AIDS Memorial. Once upon a time, this is where I stood guard as a fourth-grade street-crossing monitor from P.S. 41, the school up the block, until my boss and classmate Trippy West suspended me for reporting late at the end of a lunch period. But I digress.  Neighborhood groups, along with the city’s Landmarks Preservation Commission, acknowledging the necessity for a “fan plant,” pleaded for years with the authority for a design less hideous than a windowless concrete bunker and a few forlorn benches. Transit officials paid no attention. With a chain-link fence around the base and part of a fake-brick townhouse facade, topped by a curtain-rod cornice, the facility seems an intentional slap in the face of every New Yorker who hoped for a structure that, if not actually good, might at least be innocuous.  It’s also a reminder that infrastructure projects like this were once occasions for civic-minded expressions of architectural ambition. Walk just a few blocks from Mulry Square to the three-story Metropolitan Transportation Authority substation at Greenwich Avenue and 13th Street, built during the early 1930s. Its geometric decorations, embossed aluminum doors, limestone frieze, Flemish brick coursing and square turrets make it one of New York’s Art Deco gems and a neighborhood landmark.  The contrast between the bunker and the substation can make you weep. But it also proves what a difference good architecture makes, to New Yorkers’ daily lives and to the long-term welfare of the city.  Follow Michael Kimmelman on Twitter: @kimmelman  A version of this article appears in print on December 16, 2016, on Page C23 of the New York edition with the headline: A Year of Skyline Spectacle and Joy. Order Reprints| Today's Paper|Subscribe
The Times critic Michael Kimmelman reflects on how architects have changed New York City this year, making it more livable, humane and energizing.