Medellín’s mayor, Aníbal Gaviria Correa, is obsessed with statistics, especially homicide rates. Every day he keeps a close eye on the murder tally in this city of 2.5 million people.

“As mayor, the darkest and most painful days are the ones when we have an increase in murders. The happiest and calmest days are when there’s a decrease in murders. And the best days are when there are zero murders,” says Gaviria, sitting in his office behind enlarged maps of the city and panoramic views of downtown Medellín.

Over the past two decades, Medellín has gone from being murder capital of the world to a city renowned for its much -copied urban regeneration focused on slum areas and cutting-edge transport initiatives, all of which Gaviria is forging ahead with and expanding. Back in 1991, Medellín’s annual homicide rate was 380 murders per 100,000 inhabitants. Then the city was ground zero for the world’s largest drug cartel run by native son and drug lord, Pablo Escobar, until he was gunned down on a rooftop in 1993. It meant that Medellín was far deadlier than most war zones. By way of comparison there were 59 murders per 100,000 in Iraq during the worst periods of the war. But Medellín isn’t Escobar’s fiefdom any more and murder rates have subsequently plummeted. That figure, while hardly low by European standards, now stands at 53 per 100,000.

“Without any doubt my number one priority is respect for life, co-existing in peace and building a society that’s more equal,” says Gaviria.

Improved security and the demise of Escobar’s cocaine cartel have allowed Medellín, Colombia’s second city, to reinvent itself through bold urban renewal. The renaissance is palpable. Dotted across the city’s once ignored slum areas are landscaped parks and football pitches, alongside new schools and nurseries providing free meals. One rubbish dump has been transformed into a thriving community arts centre and once abandoned public squares are now filled with sculptures and fountains. And the paisas, as the locals are known, get around using a spotless metro, something Bogotá’s residents, an hour’s plane ride away, can only dream of.

At one steep hillside slum, Comuna 13, Medellín’s most conflict-ridden area, architect Carlos Escobar is keen to showcase the latest $5m (€3.9m) project he’s been working on. At the upper reaches, overlooking the eerily quiet, narrow streets, he points to a series of covered escalators running through the middle of the slum and past tin-roof shacks.

“The free escalators are more than just a transport solution saving residents a 30-minute climb. They transcend their functional role because they connect people and make people feel proud and cared for. It helps change the way this community sees itself and raises self-esteem in an area known for its bad reputation,” he says.

He explains it’s all part of Medellín’s long-term master plan to bring state services to slum areas and integrate them with the rest of the city. Such an approach may sound obvious but it’s radical. Too often governments across Latin America simply leave slums to fend for themselves.

“These communities had been traditionally ignored by governments. That changed here 12 years ago. We’ve penetrated into areas where it was physically, socially and institutionally impossible,” says Escobar. Perhaps one of the most visible icons of Medellín’s transformation is the Spanish Library. Perched on a hillside slum, three monolithic black boulders house an art gallery, auditorium and reading rooms where pensioners and women’s groups meet and children use new computers to study.

Even more eye-catching than the library itself is the cable car leading up to it from the foot of the hill. It means residents no longer have to face an hour’s steep climb up concrete steps. It’s part of a network of cable cars launched in 2004, ferrying 29,500 people a day from the mountaintop slums to the subway system in the valley below. Inspired by its success, similar cable cars have been introduced in Caracas and Rio de Janeiro.

Many credit the city’s transformation to Sergio Fajardo, a former mayor of Medellín (2003 to 2007), who is now governor of Antioquia, the department of which Medellín is the capital. Fajardo believes transport systems and good use of urban and public space are tools to help communities integrate and live peacefully together.

It’s a vision that three successive mayors, including Gaviria, have shared. Moreover, Medellín’s mayors have had big chunks of money made available, thanks to the profitable regional utilities provider Public Companies of Medellín (epm). The energy company is owned by the city and hands over some $450m (€351.8m) a year for city development projects.

Despite Medellín’s push for urban renewal, high levels of inequality and social exclusion stubbornly remain – a scourge most Latin American cities face.

Inequality is most acutely felt in Medellín’s slum neighbourhoods. These occupy entire hills surrounding the city, and are where roughly half of Medellín’s population lives, including families who have fled their rural homes because of Colombia’s guerrilla war.

Few residents living in slum areas would deny that large amounts of political will and cash have been injected into these deprived neighbourhoods. But venture a few blocks away from the new libraries, paved streets and cable-car stations and it’s clear just how fragile change is here.

“There’s been investment in huge infrastructure projects but what’s the use if all that doesn’t lead to jobs?” says Monica Benitez, a 69-year-old who lives in Comuna 3, a warren of densely packed one-room wood-and-brick shacks running along tight stairways. “We’ve got greater mobility in terms of transport but not mobility in the sense of really improving our lives.”

In most slum areas, armed gangs working for organised crime networks still hold sway. They prey on jobless young men to become informants, arms couriers, hit men and street dealers catering to a rising demand for drugs.

The sound of gunshots still echoes through the slums at night, while the threat of being hit by a stray bullet remains a reality. In one weekend alone in March this year, 25 people were murdered in Medellín. Urban renewal can only dilute the impact of drug-fuelled violence up to a point. “You can risk your life crossing the invisible lines that mark each gang’s territorial boundary,” says Benitez. Luis Suárez, one of Medellín’s seven vice-mayors, who is tasked with security, emphasises that more and more elite police units are being deployed to the city’s troubled areas to catch ringleaders.

“Drug-trafficking is the biggest source of income for gangs, followed by extortion. Currently, rival gangs are fighting for territorial control, and to expand their control,” says Suárez, standing on the roof of a large concrete police station overlooking the Comuna 13 slum.

Down in the valley below, less than a 20-minute drive, these shanties feel like a world away. The contrast between the haves and have-nots is stark. Here in the affluent neighbourhoods of the city’s south, high-end apartment blocks with marble entrances, luxury chain hotels and flashy shopping malls line clean streets.

By day, the fashionable El Poblado neighbourhood with its clothing boutiques, art galleries and outdoor cafés has a laid-back and villagey vibe. By night, during the weekends, glitzy rooftop clubs are filled with paisas dressed in hip-hugging skirts, gyrating to the sound of live Latin music. Surrounding the leafy Parque Lleras square, bars packed with well-heeled and educated locals spill onto the pavements, lending a festive atmosphere to the year-round balmy evenings.

And when paisas want a break from the city’s frenetic nightlife, they don’t have to go far to find a mountain wilderness with lakes and hiking trails at the Arvi Park, about an hour’s drive from downtown Medellín.

It’s this side of Medellín, along with generous tax breaks, that in recent years has attracted the likes of technology companies Hewlett-Packard and Unisys to set up shop here.

It’s hoped such new foreign investment to Medellín will create jobs in a city where, like Bogotá, the unemployment rate stands at about 12 per cent. Industries such as tourism, health, construction and IT have been singled out as growth areas, to offset the languishing textile and coffee sectors that have traditionally been the mainstay of the local economy.

Last year, Medellín beat off stiff competition from Brazil as the place for multinational Kimberly-Clark to build a global research centre. “We chose Medellín because of the engagement of its people, their entrepreneurial culture, the strong network between the public, private and academic sectors, and Colombia’s good intellectual property rights,” says Andrea Orifici, an Argentine who heads the research centre lying in verdant hills outside of Medellín.

And she’s keen to add that attracting employers to the research centre isn’t such a hard endeavour, with Medellín’s “perfect climate, not-so-bad traffic and friendly locals”.

Colombia’s corporate giants based in Medellín don’t have a hard time attracting a talented workforce either. There is Grupo Sura, the country’s second-biggest financial group; Bancolombia, Colombia’s largest bank by assets; Grupo Argos, the leading cement producer; and Grupo Nutresa, Latin America’s fourth-largest food company in terms of market capitalisation. All are helping to consolidate Medellín as a growing business and financial hub.

Straddling the city’s north-south divide is the botanical garden in downtown Medellín. Only a decade ago, it was considered too dangerous to visit and lay derelict. Yet its fortunes were turned around under the helm of Pilar Velilla, the garden’s director at the time. The free botanical garden, adorned with palm tree and bamboo woods, is now a sanctuary. It’s in many ways a less-conspicuous but potent symbol of the city’s revival.

“People from the south and north neighbourhoods don’t know each other. It’s still a divided city, but here you can see a couple having a Champagne picnic sitting next to a humble family eating hot dogs. Public space is an equaliser,” says Velilla, walking across a manicured lawn as an iguana scurries past.

Designed by local architects, the garden’s centerpiece is a vast hexagonal canopy housing a collection of more than 3,000 orchids. “The city needs to be extravagant in terms of being generous with public space where people can relax. It’s a process of seduction,” says Velilla.

Another paisa forging ahead with his own process of seduction is a 27-year-old rapper and community activist known as Jeihhco, who lives in the upper reaches of Comuna 13.

Through his group of local rappers, Jeihhco aims to steer children away from the pervasive gang culture by offering break-dance, graffiti and rap lessons at his hip-hop school, which attracts 200 youngsters every week.

“We want to be the alternative to gangs on the street. We want to show kids there’s another path and allow them to have fun in such a difficult context and environment,” he says.

“When you walk around the comunas the only option you see all the time is war. Whether it’s a policeman or gang member, there’s always a man holding a gun. You’re on alert the whole time. We need to recover our territory and get kids out of the conflict.” He is by no means alone in his desire to see change. It’s a priority for Medellín’s mayor too. To maintain the city’s revival and progress on murder rates, initiatives that help keep children off the streets and prevent them from joining gangs in the first place are fundamental.

It is why, the mayor says, more money is being spent on expanding after-school sports and arts clubs, youth orchestras, building multi-use community centres in slum areas, and providing more university scholarships.

“We need to continue to attack certain forms of indifference and further promote a culture that respects life, laws and transparency. It’s about exalting positive values, like work, respect and solidarity,” says Gaviria. And perhaps it’s the promotion of such values that is ultimately the hardest part of Medellín’s modern transformation.

Rapper Jeihhco points out that a still dominant drugs culture, in part a legacy of Escobar’s era, influences social mores. “Under a narco culture, life is cheap and disposable, and making a quick and easy buck requires no education,” he says. It means the role model is too often a drug trafficker.

“Kids in the comunas want to belong, they want respect and to be recognised just like anyone else. But the point is how one gets that recognition and respect.

It’s when the narco is no longer the only way out, the only option to get ahead, the only way to earn status and get the beautiful girls and nice cars. It’s about breaking that mind-set. And that’s the real transformation.”

1. The city is about to get a waterfront makeover. “One of the most exciting projects is the riverside avenue park. There is 20km of river in the city and we aim to recover this water as a natural feature and space for citizens,” says Jorge Perez, Medellín’s urban planning director.
2. One of mayor Gaviria’s signature projects is building a green belt, complete with landscaped parks, gardens, paved walkways and cycle routes, situated on top of the city’s hills.
3. A new tramway connecting downtown with poor neighbourhoods in the eastern part of the city aims to reduce travelling time and traffic.

1. Provide cheaper loans and tax breaks for small- and medium-sized textile companies and fashion designers to stimulate the city’s ailing textile industry.
2. Raise awareness outside Latin America that Medellín is the regional leader and pioneer in transplant operations to generate more jobs and health tourism.
3. Promote community policing to offset the view that police are only used to quell waves of violence in troubled areas.
4. Resolve land tenure issues and sort out property titles for hundreds of thousands of displaced families living in illegal settlements in slum areas.
5. Sponsor industry and business leaders to become positive role models and mentors for school children.