Every city has its own unique challenges, which are all the more difficult now that millions of people are pouring into cities in search of better lives. But while metropolises are magnets for better-paying jobs, the competition for these, as well as for housing, food, water and personal space, often dims the promise of a city's bright lights. It takes gutsy mayors with clear vision, compassion and a commitment to thinking out of the box to make a city that everyone, not just the privileged, can really call home.
Cheong Suk-Wai and Grace Chua talked to three such mayors at the World Cities Summit this week to learn how even cities facing the most desperate, desolate and daunting circumstances can become places that are the envy of the world.
Anibal Gaviria Correa, 48, has been the mayor of Medellin, Colombia's second-largest city, since 2011. The married father of four was the governor of Medellin's parent province, Antiquioa, from 2004 to 2007. In 2007, the independent body known as the Leader Colombia Project named him Colombia's best governor.
In Singapore, cable cars are used mostly by tourists, but Medellin mayor Anibal Gaviria Correa has made them a part of his city's public transport system. Most of Medellin's 2.4 million people live in the mountains around the flat centre of the city, which was once called the world's most violent capital as it was in the grip of guerillas funded by drug lords.
It used to take Medellin dwellers 11/2 hours to go downtown. Now, with the cable car system connected to the new sleek US$350 million (S$440 million) downtown tram system, they can complete that trip in 15 minutes.
But he has a deeper reason for introducing this speedier, easier commute. He told The Straits Times at the World Cities Summit on Wednesday: "Many people think Medellin's big problem is violence, but our even bigger problem is inequality and inequity. So one of the fundamental solutions to social injustice is to give young people opportunities to expend their energy and create public spaces in which everyone is equal."
So, besides the cable cars and trams "in which everyone is equal", he has introduced library parks where everyone can gather, borrow books from mobile libraries and read and discuss together; as well as art, music and sports events for young people.
His creative ways to help everyone have a better life led global non-profit think-tank Urban Land Institute to name Medellin the world's most innovative city last year over New York City and Tel Aviv.
His city's homicide rate has plunged from 280 per 100,000 people before 2004 to 28 per 100,000 people today. Although his term as mayor ends next year, he is working on two big projects.
The first is the US$1 billion Medellin River Park, where he will build lots more mixed riverside developments, especially housing for all tiers of society.
The second is the US$500 million Green Belt, a ring of parks on the city centre's fringes which people are not to build on. This, he said, would nudge Medellin's inhabitants into spending more time in the city centre instead of its outlying mountains.
The Harvard-trained Mr Correa said: "The tough situation in Medellin motivated me to go back and oppose violence." So it was that in 2004, he was elected by the people of Antioquia to take over after their previous governor, his elder brother Guillermo, was murdered by terrorists.
ROTTERDAM, THE NETHERLANDS
Ahmed Aboutaleb, 52, who migrated to the Netherlands from Morocco at age 15, has been mayor of the Dutch port city of Rotterdam since 2009. Prior to that, the married father of four was chair of multicultural development organisation Forum, then an Amsterdam city councillor. Last year, Rotterdam was selected to receive help climate-proofing itself by the Rockefeller Foundation's 100 Resilient Cities challenge.
THE Dutch port city of Rotterdam faces many of the same challenges as Singapore.
It is low-lying - 80 per cent is below sea level - and vulnerable to floods. Droughts, too, affect drinking water supplies. And its 600,000 or so people from 174 different countries, nearly half of whom are not of Dutch origin, must work out how to get along.
Yet ask its mayor Ahmed Aboutaleb what his biggest idea to improve the city is, and he will say it is education.
Mr Aboutaleb, in Singapore for the World Cities Summit Mayors' Forum, said: "What I witnessed here was that every mayor is keen about his own projects, whether it's bike lanes, bus systems, more green...
"But one of the biggest issues I face when talking about climate change and water is raising awareness. Are our citizens educated enough to know what is going on? Are they aware enough to be responsible for possible future situations?"
So Rotterdam is footing the bill to keep schools open an extra eight hours a week for students to learn - "not just classroom learning, but going into the forest, visiting the library, and so on", Mr Aboutaleb said.
Most politicians prefer to invest in big visible projects like bridges rather than education, which is not even a sure bet, he said. But Rotterdam will need an educated population to face environmental and social challenges.
For instance, periods of high water are more frequent today. Last year, the city secured funding from the Rockefeller Foundation's 100 Resilient Cities challenge to retrofit buildings in low-lying areas, turning their ground floors into a flood barrier.