Inside New York City Planning Director Amanda Burden’s office a block from city hall, a huge photograph of Brooklyn’s waterfront leans against the wall. It’s not a pretty image. Dotting the East River are two miles of grungy warehouses, largely abandoned, with chain-link fencing choking off the river from the city.

It’s the same scene that Burden showed Mayor Michael Bloomberg when she took him on a tour of New York City more than 11 years ago, back when he was just starting to consider a run at the city’s highest office. The tour along that waterfront, Burden says, was an emotional experience, since both she and Bloomberg saw an amenity that New Yorkers could potentially be enjoying but instead had long been denied.

Today, as Bloomberg’s third and final term in office is drawing to a close, it’s clear that the meeting had an impact on both of them. The two have taken to referring to New York’s waterfront as the city’s “sixth borough,” and developments along the water -- from Brooklyn Bridge Park in Brooklyn to Freshkills Park in Staten Island to the East River Esplanade in Lower Manhattan -- have been among the administration’s highest-profile undertakings.

Those projects have been touted as economic development drivers, and they are. But just as important, they’re key to the idea of livability -- that sometimes hard-to-define concept that makes it enjoyable to call a certain place home. “In the end, great public space is what makes people want to stay in the city,” says Burden, who’s held her position since Bloomberg first took office. “You live in this high-density, high-energy environment. These waterfront parks just changed how people feel about the city.”

Bloomberg’s time in office has been about much more than parks, of course. America’s most famous mayor has gained international attention for his ardent advocacy on issues like gun control, immigration reform, infrastructure investment and climate change. More controversially, he’s well known -- and sometimes lampooned -- for enacting bans on trans fats, smoking in public places, and big, sugary beverages. But for New Yorkers, Bloomberg’s most important legacy -- the one that affects their daily lives most -- may be the role he’s played in reshaping the urban landscape. If predecessor Rudolph Giuliani was the mayor who made New York a safer place to live, Bloomberg is the guy who’s made it a more pleasant one. Through an unprecedented emphasis on parks, pedestrians and development, Bloomberg’s signal achievement could be the physical transformation of the city. His commitment to livability has put an indelible imprint on Gotham. Now, his mayoral tenure is coming to an end; a new leader will be elected in six months. And there’s one question that underscores every conversation about the upcoming election: Can the momentum of the Bloomberg years continue?

There’s a small park in SoHo called Lieutenant Joseph Petrosino Square. For decades, it was hardly more than a forgotten concrete triangle surrounded by streets on all sides. As Mitchell Moss, a New York University urban planning professor and media-dubbed “New Yorkologist,” walks past Petrosino Park, he says it was a “shithouse for meth heads” until a few short years ago. Then things changed. The city (in a $2 million project championed by former Councilman Alan Gerson) enlarged the park and added new benches, trees and lighting. Today, it’s a tony greenspace for neighborhood residents, workers and shoppers, who meet in Petrosino to share lunch, walk their dogs or just take a break. “Up until now, most mayors viewed parks as something they could cut,” Moss says. That’s changed, in dramatic fashion.

Petrosino Park is a small-scale example. Brooklyn Bridge Park is a much larger one. Creating a park along Brooklyn’s disused post-industrial waterfront has been the subject of debate for 30 years. “Now it’s one of the great gems of the city,” Moss says. Progress is continuing on the 85-acre park, with bocce courts, soccer fields, summer concerts and even the occasional pop-up swimming pool. And there’s an even bigger example on Staten Island, where the Fresh Kills landfill is being transformed into a 2,200-acre park. That project, which has been under way since 2008, will result in the largest park developed in the city in a century.

And, perhaps most famously, there’s the completion of the High Line, the internationally known project that wrested a spectacular linear park from the ruins of long-abandoned elevated railroad tracks in Chelsea. The mile-long park has significantly altered the neighborhood around it, attracting tremendous new development and becoming a favorite spot for residents and visitors alike. “High Line” has become shorthand for planners and activists worldwide who want to transform the derelict into something dazzling.

“I think for a good 50 years, there was a sense that this is our city, and we’re stuck with it,” says Aaron Naparstek, a fellow at Harvard’s Graduate School of Design and founder of the website Streetsblog, which covers land-use and transportation policy in New York. “One of the really great legacies of the Bloomberg administration is going to be this sense that we can change things.”

“We clearly have moved into a new era now where people see that it’s really possible to redesign New York City streets, the waterfront, the public spaces and the parks,” Naparstek continues. “These things are not just set in stone. These are things that we have control over.”

Indeed, Bloomberg observers say he’s been successful in making major changes in the city -- and getting them done quickly -- for two big reasons. For starters, he’s a political outsider who is independently wealthy, making him beholden to nobody. “He’s not afraid to take risks,” says Robert Lieber, who served as Bloomberg’s deputy mayor for economic development from 2008 to 2010. “He’s not going to play it safe all the time.”

Bloomberg also has a reputation for avoiding micromanagement, empowering his deputies and loyally defending them from any political fallout they may encounter. Those close to him say that while livability is absolutely one of the mayor’s priorities, he’s comfortable deferring the specifics to his lieutenants. “Really, he gives you an enormous amount of leeway to come up with your plans,” Lieber says. “He’ll support you and defend you. This is what a chief executive does. He knows how to run a business. If you’re going to be effective at running a business, your effectiveness is being able to leverage the people that work for you.”

Janette Sadik-Khan has perhaps been the biggest beneficiary of an administration that has been unafraid to shake things up. As Bloomberg’s transportation commissioner since 2007, Sadik-Khan has transformed the role of her office by placing a serious emphasis on pedestrians and bicyclists. Under her leadership, the city has created 300 miles of bicycle lanes. She’s been on a quest to make streets safer and more accessible to those who use modes of transportation besides driving. (As she points out, only about one-third of New Yorkers regularly drive.) And she’s probably not exaggerating when she says her office has made the most significant changes to New York’s roadways since one-way streets were introduced 50 years ago. “Our streets were out of balance,” Sadik-Khan says. “They were not designed for the demands that are on them today. That’s really what we’re doing. And we’ve gotten a lot done.”

In addition to the unprecedented proliferation of bike lanes in New York, the department this spring will help launch the largest bike-share program in the country, capitalizing on an urban amenity that has proven extraordinarily popular in other cities. And throughout New York, Sadik-Khan’s department has embarked on an ambitious plaza program: Using planters and other barricades, the city has blocked off parts of some streets to establish pedestrian plazas with benches and chairs. (Unsurprisingly, much of her work has been praised by those who don’t use cars, and demonized by those who do.)

Among the most prominent of the new plazas are those in Times Square and further south along Broadway, where pedestrians lounge or stroll along streets that were, at one time, major thoroughfares filled with honking cars. “Times Square -- that whole area -- was just a Gordian knot of traffic,” Sadik-Khan says. “Ninety percent of the street was dedicated to cars, yet 90 percent of the people there were pedestrians. It was really out of balance. People don’t go to Times Square to see the traffic.”

Like others throughout the Bloomberg administration, Sadik-Khan focuses intently on data, and she uses it to help justify her programs. She says pedestrian deaths are down and business is up in places that have gotten the pedestrian/bicycle overhaul from her department. Still, that doesn’t always make her popular. She’s frequently been criticized by New York tabloids. The New York Post calls her the “psycho bike lady;” Brooklyn Borough President Marty Markowitz calls her a “zealot.” And the bike lanes have even become the subject of lawsuits.

Sadik-Khan says she doesn’t worry about the political implications of her department’s initiatives -- and that’s something she says she has in common with her boss. After all, Times Square was pedestrianized in 2009, an election year. A mayor with a more conservative style might have waited until after November to pursue such an unusual undertaking, Sadik-Khan says. “I remember him telling me at the time, ‘I don’t ask my commissioners to do the right thing according to the political calendar; I ask my commissioners to do the right thing, period.’ I think that pretty much says it all.”

Still, Sadik-Khan (and Bloomberg by proxy) have been criticized for their hardball techniques. Her office has a reputation for literally transforming streets in the dark of night, which some believe is intended to make it difficult to block the work. The New York Times has chronicled a technique used by the administration -- and in particular the transportation department -- to launch projects as “pilots,” as a clever way to cut through red tape and escape the typical city review process. When asked about her reputation as someone who’s more effective at getting things done than building consensus, Sadik-Khan is unapologetic. “We really didn’t have a choice. Our streets had been in suspended animation for 50 years.”

Amanda Burden, the planning director, is the other half of the administration’s team that has played a significant role in reshaping the city. Her approachable demeanor and affable tone belie her status as what some observers call the most influential person in the city’s political power structure besides Bloomberg himself. She’s been described as a woman with the ideals of Jane Jacobs and the power of Robert Moses. “If you’re in love with cities, you say, ‘What are the qualities that make me want to be in the city?’” she asks rhetorically as she explains her philosophy. “It’s fun. There are choices. It’s diverse, and [there’s] always a sense of change -- something new and exciting. It’s a sense of serendipity.”

A former socialite and an heir to the Standard Oil fortune, Burden eschewed a life of privilege for a career in urban planning. She has worked on the City Planning Commission since 1990; when Bloomberg took office in 2002, he appointed her chair of the commission and head of the Planning Department. Since then, her office has led an ambitious program that has rezoned an unprecedented 40 percent of the city. To those not steeped in the world of planning, that accomplishment may not sound noteworthy. But it’s been an integral part of opening access to the waterfront, facilitating parks improvements and developing land-use patterns most suited for the city’s future population growth.

Bloomberg has elevated the prominence of planning and zoning issues, giving Burden’s office unmatched influence and facilitating initiatives like the Hudson Yards Redevelopment Project, a mixed-used real estate development being erected over a train yard along the western edge of Midtown Manhattan, or the development of Lower Manhattan’s Seward Park, which will create a mixed-used space on six acres of underutilized land that will include a new market, commercial space and affordable housing. “People knew the status quo wasn’t acceptable,” says Moss, the NYU professor. “There was recognition that doing nothing was no longer valuable.”

In New York, development occurs “as-of-right,” meaning that if a developer wants to build something that conforms exactly to the existing zoning standards, he can do so with little more than a building permit. In reality, the city’s zoning regulations are so outdated that developers frequently need special approval. The administration, through Burden, is changing those zoning guides to upzone for higher density in areas that are transit hubs like Jamaica, Queens; Downtown Brooklyn; and Long Island City -- and downzone in areas that aren’t suited to big growth. Eventually, the goal is to make as-of-right development widespread, so that developers don’t need special approval. “The concept of setting the table to allow these neighborhoods to grow and change is a positive thing,” says Mitch Korbey, a land-use attorney and director of the planning department’s Brooklyn office under Mayor Giuliani.

As Burden has gone through that process, she’s gotten creative. In addition to using the traditional tools of her profession -- things like height limits and setback requirements -- she’s including provisions that encourage bike parking, environmental components and affordable housing. “We use zoning for a variety of different things that nobody’s even thought about,” Burden says.

The city’s most creative rezoning effort has been the High Line. In addition to being one of the earliest champions of the park itself, Burden created the rezoning mechanism that helped make the work possible. Owners of land underneath the rail line had wanted it demolished since it kept them from building vertically. Her office allowed landowners to sell those air rights to nearby sites where higher developments would be permitted. That’s caused a real estate boom in the area surrounding the park, a stretch along the west side of Midtown Manhattan that had long been underdeveloped.

Burden has gained a reputation for having a granular focus on aesthetic design details. Supporters say that fine eye has served the city well, but some developers have called it strong-arming, and have accused Burden of overstepping her bounds as a civil servant. “From the outset,” says one developer, “everyone was aware -- and has been aware -- that Amanda has to like it, or it won’t happen.”

Like Sadik-Khan, Burden makes no apologies for her style. “We’ve tried to raise the bar for what’s expected in design. And that has really been important, not only for iconic, cultural buildings, but in areas like the South Bronx” where thousands of new housing developments are being built, she says.

And even if some developers have bristled at Burden’s approach, it has served New York well, says Korbey. “Projects are better because of this. The city now has more attractive and exciting architecture.”

New York is a better place to live now than it was a decade ago. It’s difficult to find anyone who would dispute that sentiment. But can the progress on livability continue once Bloomberg has left office? Will the next mayor build something like the High Line? Will Bloomberg’s successor tackle anything as ambitious as transforming Times Square? It’s unclear, thanks in part to the wide-open field of candidates. Among them are Christine Quinn, the speaker of the New York City Council who’s seen as Bloomberg’s heir apparent; Public Advocate Bill de Blasio; Joseph Lhota, who recently resigned as chairman of the Metropolitan Transit Authority; Bill Thompson, the former city comptroller; and Joseph Liu, the current comptroller. There’s a common thread here: All of those candidates come from typical political proving grounds. Moss, the planning professor, calls them an uninspiring bunch, and he warns of a possible “return to normalcy” under any of them. (John Catsimatidis, the billionaire owner of the Gristedes grocery store chain, announced his candidacy in late January; he hasn’t held office before, but his candidacy is considered by many to be a long shot.) While there are many candidates, they’ve said little or nothing about what they plan to do with the city’s physical space.

However it shakes out, Streetsblog’s Naparstek says, New Yorkers will likely miss the independence that comes with a billionaire mayor who’s a political outsider. “They’ll get a reminder of what it’s like to have a regular old Democrat back in city hall who really feels like he or she has to take heed and pay attention to whatever cranky rant is coming out in the Daily News on Thursdays,” Naparstek says. “Mayor Bloomberg did have a unique ability, for better or for worse, to ignore a lot of that stuff and didn’t really feel so beholden to it. The next mayor almost certainly is not going to be insulated.”

Some urban advocates are concerned not just about livability in the abstract but about whether some of the administration’s efforts may literally be undone. De Blasio has called Sadik-Khan a “radical,” and Quinn has said Sadik-Khan’s style has contributed to the controversy surrounding bike lanes. Some wonder whether the next mayor would literally start removing bike lanes.

And there are those who actually are leery of the Bloomberg livability campaign. Bloomberg’s critics say the rash of development under his leadership has been a boon for developers and gentrifiers but has done little to benefit the average New Yorker. Marquee parks and public spaces are great for wealthy residents, 20-something urbanites and tourists, but critics say they haven’t helped working-class families. “Is New York becoming a luxury item? And is it affordable the way it used to be?” asks Joseph Viteritti, chair of Hunter College’s Urban Affairs & Planning Department. “These are the issues that I think will come up.”

The administration doesn’t put much stock in that criticism. “A growing city is a good thing,” Burden says. “I don’t think you’d turn your back on that.”

Indeed, the administration often works hand in hand with community groups on many improvements like parks and plazas, says Bruce Berg, a political science professor at Fordham University. Those groups, now that they’re mobilized, could continue to demand similar efforts under Bloomberg’s successor. That’s a notion echoed by Sadik-Khan, who says that in many cases the transformations happening in New York are more of a response to the wants and needs of residents than the product of anyone’s political agenda. “A lot of times,” says Sadik-Kahn, “the public leads the political officials, and I think that’s the case here.”

That may be true. But there’s still a sense among many observers that it will be difficult for any successor to match Bloomberg’s impact on the overall look and feel of New York City. “I think it’s going to be very hard,” says Moss, “for any mayor to equal what Mike Bloomberg has done.”