MEXICO CITY — The plan is as big as this mammoth city: Turn a seedy metro hub into Mexico City’s Times Square; clear swarms of feisty vendors and remodel the historic Alameda Central; illuminate the plazas and walkways of a park twice the size of New York’s Central Park.
Mexico City’s government is trying to transform one of the world’s largest cities by beautifying public spaces, parks, and monuments buried beneath a sea of honking cars, street hawkers, billboards, and grime after decades of dizzying urban growth.
Despite the challenges, the ambitious, multimillion-dollar program carried out by Marcelo Ebrard, former center-left mayor, and continued by his successor, Miguel Angel Mancera, is winning praise from urban planners and many residents. And it’s turning the metropolis into an experiment in how to soften urban sprawl.
‘‘It’s time to tame the city,’’ said Juan Carlos de Leo Gandara, head of the Iberoamerican University’s sustainable urban projects. ‘‘Today is about giving the city back to pedestrians.’’
In the Alameda, made iconic in the Diego Rivera mural ‘‘Dream of a Sunday Afternoon in the Alameda,’’ concrete sidewalks were replaced by marble, and makeshift vendor stands were kicked out — a renovation that cost about $18.7 million.
Instead of a patchwork of folding tables and tarpaulins, the newly opened park, which includes the art nouveau Palacio de Bellas Artes theater, is an expanse of greenery and calm in the midst of racing traffic.
‘‘It used to be very dark, with no lighting. It really wasn’t a place to bring my son,’’ said Alma Rosa Romero, a 22-year-old housewife standing by the new dancing-water fountains, holding her child’s hand. ‘‘Now it’s beautiful.’’
Other completed projects include a once-neglected plaza with an Arc de Triumph-style monument to Mexico’s 1910 revolution, which has been remade at a cost of $28.6 million from a homeless encampment to an oasis where families frolic and children run through spurts of water gushing out of the pavement. The copper dome of what started out as the country’s Congress building is newly polished and gleaming.
Downtown, at the Chapel of the Immaculate Conception of Tlaxcoaque, the city has installed multicolored fountains that light up at night and replaced a parking lot with a larger plaza for pedestrians.
The city has also converted Gustavo I. Madero street in the historic center into a pedestrian walkway stretching to the Zocalo, the plaza that’s home to the National Palace and massive Metropolitan Cathedral. And under a popular bridge near the hip neighborhood of Condesa, the city made way for a taco joint and a playground.
‘‘A city where people go out to the streets is safe, happier, and raises the quality of life,’’ said Daniel Escotto, chief architect of Mexico City’s Public Areas Office, which was founded in 2008 to manage urban renewal. ‘‘We are renovating floors, facades, and adding plants and lighting and more elements that can shape this concept.’’ Yet in a city defined in many ways by its disorder, the plan is also being slammed by those who take pride in surviving the urban jungle.
‘‘Yes it’s safer, and it’s renovated, but what happens to the emblem of Mexico City?’’ said Baltazar Romeo, 47, a hospital worker eating a sandwich at the newly remodeled Alameda. Gone were the street performers who once dressed as the Three Wise Men during Christmas and charged tips for photos with children.
‘‘The city is becoming soulless,’’ Romeo said. One of the flagship renovation projects is the once-seedy, swarming Glorieta de Insurgentes roundabout and metro station in central Mexico City, which sees hundreds of thousands of commuters pour through every day.
The circular plaza was sunk to let pedestrians stream below busy thoroughfares and catch their trains or buses or just hang out. Around its rim careen cars in a roundabout that briefly merges two of the city’s biggest thoroughfares, the mighty Insurgentes and Chapultepec avenues.
When the plaza was built in 1969, the city’s top priority was moving an onslaught of cars and people from one point to another. Highways and beltways elsewhere went up to cope with the population boom, and sprawl spread farther out.
Once-famous and safe streets and plazas suffered from neglect by planners and became slum-like neighborhoods people avoided after sunset. A brown haze covered the new skyline as motorists became the focus of the new infrastructure.
The Insurgentes roundabout turned into a place to hurry through. Homeless people took over abandoned warehouses nearby while surrounding office and apartment buildings fell into disrepair. Many of the plaza’s shops became sleazy Internet cafes cowering beneath giant billboards.
‘‘It couldn’t be more hostile to public life or pedestrian life,’’ said Ken Greenberg, a Toronto-based architect and urban designer who recently visited Mexico. ‘‘The whole thing just has a kind of very harsh feeling of a highway right in the middle of the city.’’
Urban designers are now seeking to infuse the chaos with the glitzy excitement of Times Square or London’s Piccadilly Circus. Sixty-foot cylinders covered with circular screens streaming LED tickers have been erected. The crabgrass-filled flower beds and low benches used as skateboard launches have been bulldozed for a sleek open-air look bathed in white, patterned concrete.
The makeover is meant to create a more appealing space for commuters using bikes and public transit in a city that won infamy as the world’s most painful for commuters in a 2011 IBM survey.
‘‘What Mexico City needs is to emphasize its identity through its public spaces,’’ Escotto said.