Marton Sadler with wife Agata and child Olivia. He travels 25 minutes to play in a grassy area with Olivia from their Southbank apartment. Credit:Paul Jeffers Today the elementary student shares a room with his younger brother Jace, 6, in the family's neat two-storey unit. The boys' beds are folded into a cupboard every morning so they have their own play space during the day. When The Sunday Age visits one Thursday evening the youngest son was bouncing about the unit with impatient energy. "Can you keep it down?" says their mother after Jace set off a loud electronic toy. "Only use soft balls please!" It is an upbringing that seems light years away from the so-called Great Australian Dream of the quarter-acre suburban block, where momentarily manic kids can be dispensed to the big grassy backyard. But as cities such as Melbourne prepare for enormous population growth, the lessons learnt by Manhattan's high-rise parents are becoming increasingly relevant.

Siblings Marlon and Mia Cirker shared a room in their family's two-bedroom Manhattan high-rise flat until they left for college. Victoria's capital is forecast to reach up to 9.8 million people by 2061, making Melbourne busier than modern-day London. Unless the extra 4 million people are to be exiled to the far infrastructure-poor fringes, Melbourne will have to get higher and denser. And that means more families will be living in apartments. In the Ditmyers' high-rise building in the midtown neighbourhood of Hell's Kitchen, children have been growing up in apartments since the 1970s. The Gentlemen of Docklands group meet each morning for coffee at the Mad Duck Cafe. From left to right. Shaun Bassett, Matthew Selleck, Trevor Rowe, Ian Johnson and Kim Rea. Credit:Emma Morgan Manhattan Plaza was originally built as luxury housing estate, with spacious bedrooms, large balconies and sunset views of the Hudson.

Today it is estimated a two-bedroom unit in the building would fetch about $67,000 a year in rent but in the late 1970s the neighbourhood was rough and gritty and the units simply would not sell. Christine and Jason Cirker with son Marlon and daughter Mia. The children spent their childhood sharing a bedroom in a Manhattan high-rise, before leaving for college. As a solution, the building was repurposed as federally-subsidised housing largely for performing artists. In those early days the arts community was suffering disproportionately from HIV/AIDS and Manhattan Plaza reportedly saw more deaths from the disease than any other block in New York City. Since that time the estate with a population of about 3500 people has been recognised as a breeding ground for showbiz stars. Possibly its most famous former resident is R&B singer and 15-time Grammy winner Alicia Keys, who was born in Hell's Kitchen and grew up in the building with her mother, a paralegal and part-time actor. The social housing block also had a crucial part in the birth of hit American sitcom Seinfeld. The television show's creator Larry David lived in Manhattan Plaza for six years across the hallway from comedian Kenny Kramer, his inspiration for Seinfeldcharacter Cosmo Kramer.

Christine and Jason Cirker have lived in the tower since 1990. They are eligible for the housing as an actor and jazz musician. Their two children, son Marlon, 21, and daughter Mia, 18, were raised in the same bedroom in their 40th level apartment until they recently moved out to attend college. Far from creating enemies of the children, their shared quarters forced them to become incredibly close. Marlon, an aspiring rap artist, says although it would have been nice to have some privacy from time to time, his sister was his best friend. "We get on really well," he says. "We learnt about give and take, and being respectful from an early age. "I have a [college] roommate now who has no idea of the unwritten rules of living with another person."

Christine and Jason says living in an apartment for 25 years was made possible by the building's unique community – a thriving vertical neighbourhood that sees children on Halloween haunt the hallways rather than the local streets. The Cirkers know everyperson on their floor. So, when on New Year's Eve 2000 none of the parents could find babysitters, the floor held a "progressive" from unit to unit. Like a "pub crawl" in Australia, the parents went from one apartment to the next, where everyone held their own party. The building also holds a twice-yearly clothing and toy exchange, that sees second-hand items are passed from household to household to save money. The only downside, says Christine, was when you realised that you were accidentally looking at the wrong child on the playground – someone else's child dressed in your child's old clothes. Seinfeld creator Larry David once described Manhattan Plaza as "unlike any other building [he's] been in". It is the sort place that you would always find a helping hand if it was needed - where cards are signed in the lobby for the arrival of a baby and the death of a resident.

But it is a different dynamic altogether in Melbourne's burgeoning high-rise precincts, where very few plan to stay for good. Southbank resident Marton Sadler, 49, has been living in the same building for more than four years but admits if he needed help carrying furniture he would not know whose door to knock on. "People come here knowing they won't be here for a very long time, so they don't go out of their way to make friends," he says. There are a small but growing population of families adrift among the young people and retirees who dwell in the skyscraper neighbourhoods of the world's most liveable city. The 2011 census found there were 215 children aged up to four years old in Docklands, a neighbourhood of almost 6000 people. There are significantly fewer primary-school-age students, meaning parents are packing their bags and heading for the suburbs when its time for them to consider their children's formal education.

It is a similar scenario in Southbank where there are about 305 children aged up to four years old but just a handful of older kids recorded during the past census. Families living in apartments in or near the CBD say the convenience of living minutes from work is the key reason for their lifestyle choice. Jarrod Jeremiah, 41, a financial planner who lives in Southbank with his wife and two young daughters says he has no desire to have to make a long trek into the office every day. "At 6am in the morning the roads are pretty busy," he says. "I have no concept or understanding of what that commute is like." But despite the apparent willingness of some families to live in towers, Melbourne City Council planners say the market is failing to meet the demand for affordable child-friendly apartments. Late last year 96 per cent of more than 20,000 apartments planned for the inner-city had two or fewer bedrooms.

Meanwhile, the council predicts there will be 14,693 children aged up to 14 living in the City of Melbourne come 2035 (an increase of about 70 per cent). A major sticking point remains the lack of a CBD public school. Docklands mother and local campaigner Janine Standfield says she had received a number of calls from people who wanted to move into the area but were holding off until a school was guaranteed. Many consider the school the magic ingredient needed to create a genuine neighbourhood, where boys and girls grow up among Melbourne's skyscrapers. Standfield says if a primary school had been built alongside Dockland's new state-of-art library, the suburb would have had "instant community". Having raised two children to adulthood in a New York apartment, the Cirkers have strong opinions about the things needed to make high-rise living work for families. Their advice echoes what the experts say is best-practice urban design that often gets forgotten along the way by developers and government.

Christine says it is essential that schools are built in high-rise districts, even when units were originally marketed at childless young professionals. "They're obviously going to have sex and they're obviously going to make babies," she says. The couple say Manhattan Plaza had been a success because children had places to play and parents space to gather. The tower's generous third-level basketball court and playground has a view over the treetops to the Empire State Building. Jason says: "If they start building a whole lot of high rises in Melbourne make sure they have some space – make sure they have some community areas". Marton Sadler and other Melbourne CBD parents are already calling for more green space around neighbourhoods rapidly being filled by even taller towers. He says there is no decent space for children close to his home in Kavanagh Street, Southbank. As a result he usually travels about 25 minutes daily to another suburb for play time with his three-year-old daughter Olivia.

Meanwhile, Manhattan has plenty of its own problems. With average monthly rents of $3836, living on the island is becoming increasingly difficult, even for the educated middle class. The Cirkers and Ditmyers pay a capped amount of 30 per cent of their income to live at Manhattan Plaza. Tamara, an actor, estimates that the discount saves the family at least $US3500 ($4500) a month. Without the subsidised housing, she says, "we would be in some other state or probably in one of the outer boroughs". Trade-offs are inevitable while attempting to live with a family in the city that never sleeps. Being in Manhattan has allowed the parents to pursue their artistic careers and expose their children to a kaleidoscope of cultures and people. Though not all their brushes with New York life have been positive. One day Marlon was playing outside when a man jumped out from one of the apartment windows, landing dead on the basketball court in front of the children. "The kids tend to be very savvy because they have to learn a lot. It's a trade-off but I don't regret it. I like who my children are as people," Marlon's Christine says.

With all its highlyeducated artist residents, politicians like to joke Manhattan Plaza is home to more school PTA presidents than anywhere else in the country. Others who live in the building are famous or on their way to it, including child actor Timothee Chalamet, who got his big break in TV drama series Homeland playing the vice-president's son. Jason says they called him "Soccer Timmy". But the building also takes a proportion of low-income families from the local neighbourhood, who are not necessarily destined for the bright lights of Hollywood or the Broadway theatres, located nearby. In other buildings in Manhattan this sort of melting pot does not exist. Similarly, in Melbourne, ugly public housing towers and shiny luxury apartments still preserve class divides. The median weekly household income is $1901 in Docklands and $1837 in Southbank, with two-bedroom homes with panoramic views currently on the market for $700,000. Average weekly rents are about $500 in both suburbs – more than a single parent on welfare payments of $360 a week could ever afford. Jason Cirker says it is a beautiful sight to watch the children of Manhattan Plaza play together, oblivious to their differences.

"We've got kids here being raised by their grandparents, we've got kids whose parents are incarcerated," he says. "I really do believe that works, when you mix people together, then you will have people starting to come together." University of Melbourne urban planning professor Carolyn Whitzman says Australians are fooling themselves if they believe the only place to raise children in Melbourne is the suburbs. She says the phenomenon of disappearing backyards was not only a side-effect of high-rise living, but a trend being experienced across the city as big houses are squeezed onto smaller lots. Whitzman says four to six storey blocks were the ideal high-rise buildings to bring up children, because they were not so tall that parents in apartments could not supervise their kids playing on street level.

"But the fact is children do grow up perfectly good in 20 storeys, it just adds extra challenges," Whitzman says. When reflecting on her sons' upbringing, New York parent Flannagan-Ditmyer points out "children only know what they know". Her boys do not consider anything unusual about their high-rise home, as even their wealthy Tribeca friends live in apartments (albeit loft apartments that take up an entire floor). Yet when Tamara was pregnant with her second child, she says her aunt was shocked to discover Tamara's children would be sharing a room together – even if the second child was a girl. Her aunt had grown up in southern Florida with beaches and swimming pools and houses so large everyone could have their own room. "She seemed to think it was crazy," Tamara says. "It was because that's all she knew."

The 3000-strong vertical community Shaun Bassett doubts anyone living in their homes in Melbourne's leafy suburbs can name 200 of their neighbours. But he can, and he has been living in Docklands for 14 years. "It's like one of those old television shows where everyone walks past, saying 'Hello Bill' and 'Hello Sam'," he says. "We've got a real community down there – 3000 people living vertically." The property developer, 47, is a resident of Mirvac development Yarra's Edge, on the south side of the river opposite the CBD.

While other tenants of high-rise areas continue to complain of segregation from their neighbours, many of the residents of this wealthy five-tower estate say they have never lived in such a close-knit suburb. The roots of this community started to take hold when a women's coffee group began, alongside a similar organisation for men, Gentlemen of Docklands, or as they also call themselves, The GOD Squad. Bassett says the group assertively reach out to new faces that arrive and gather without fail at the local coffee shop from 7.30am in the morning during weekdays. Many of them also share interest in horse racing, golf and motoring. "I drive a lot of that stuff to make sure the men connect because, honestly, men don't usually have big friendship networks," he says. Promotional material describes Yarra's Edge as "an exclusive village-style neighbourhood". It is a description that has overtones of retirement village brochure and Bassett concedes there are some similarities. Most of the people active within the community groups are in their late 50s or early 60s.

Properties with two bedrooms, two bathrooms and two car spaces are currently up for sale within the precinct for more than $1 million. Bassett says many of the young-professionals living within Yarra's Edge had high-paying jobs for their age. "It's very different to the rest of Docklands." . MANHATTAN VS MELBOURNE * There are at least 234,709 children living in the borough of Manhattan (population about 1.6 million). * The percentage of number of children in Manhattan (14.7 per cent) is well below the national United States average of 23.3 per cent.

* There are at least 6645 children aged 14 or under living in inner-Melbourne (population more than 93,600). * Between 2006 and 2011 the number of children aged four years old and younger living in the City of Melbourne jumped by 46 per cent. * The median age of people living in the City of Melbourne is 28. At least six in 10 homes is a flat, unit or apartment. Source: Census data and Melbourne City Council.