By Alistair Mackay at Future Cape Town

When you fly into Buenos Aires, the city stretches for as far as the eye can see – it's an unimaginably big sprawl of high-rise apartment blocks, urban squares and neat, rigid avenues that eventually deteriorate into slums and suburbia.

It is completely flat, and so European in the centre that I kept having to remind myself it's in South America. It looks like what you'd get if you mashed Paris and Barcelona together and injected the mix with steroids. And it is rigorously planned. A city block is always 100m, so you can calculate your distance by looking at the blocks you'll walk. It's essentially a grid, with two diagonal avenues crossing the city and intersecting at a giant obelisk that commemorates the 400th anniversary of the city.

Its scale and size made me feel a little provincial, and quite amused by the insistence of South Africa on low-density low-cost housing as a model for cities. This model simply won't work in the long-term. South Africa's developmental and social issues, although inherited from historical political design, are no longer unique. The impact of urbanization is being felt across the world and we need to learn from other cities, sooner rather than later.

We think it's "in our culture" not to want to live on top of one another, and to want a house with tons of space around it – and that has stopped projects like Red Location from working well. But it is just a luxury of timing that allows for this way of thinking. No one intrinsically wants to live in dense high-rises, but urbanization makes it the only feasible solution. Europe and the West urbanised in the 19th Century, Latin America and Asia in the 20th, and Africa is next. Their peripheries all moved from slums to high-rises. African cities are going to grow at the kinds of staggering rates that made places like Shanghai and Buenos Aires have populations like countries. And we need to wake up and start planning for reality, and not some antiquated suburban notion of a car in the garage and a front garden for every family.

I'm pretty sure that in the next 100 years the whole of Cape Town's centrally located Cape Flats area will become built up. And this can either be a planned process or a chaotic one. In the favelas of Rio, people sell the roof-space on top of their shacks to other people, who build a shack on it and sell their roof-space to someone else. The result is multi-story slum-cities built on sacks for foundations that collapse when the rains come, killing people. Single-story living is just not practical in modern cities, and especially in Cape Town, where already the distances to the city centre are cumbersome for many residents, and we are going to run out of space between the mountains of the peninsula and the Hottentots-Holland.

So if densification is inevitable, shouldn't our planners focus on ensuring this happens in a way that creates a livable city? They should be planning green corridors, urban parks, nature reserves and public squares. When people have no personal space for a garden, the need for usable public space is essential.

And this requires rethinking the idea of a city centre. As Cape Town grows, the city will gain many centres, each with their own unique feel – like Rio's Copacabana or Ipanema neighbourhoods, each of which provides something very different to its old, Portuguese-colonial centre or its downtown area. Buenos Aires has Parisian avenues in parts, bright, colourful, corrugated iron buildings in parts, and glass skyscrapers in others. How about planning for a Mitchell's Plain promenade? Or a beautiful Khayelitsha beachfront with bars, shisa-nyamas and flats along the False Bay coast that celebrate their position on the coast? We could involve residents in beautification projects like the Selaron steps in Rio.

There is no reason we can't start small. In Rio the city has built gym equipment every 500m along the beach front, so that every resident can stay fit and healthy for free. Now that is making inclusive use of public space. The choice to plan or be planned remains in our hands. Will Cape Town step up to the plate?

Future Cape Town is a social media movement aimed at inspiring citizens and stimulating debate about Cape Town today and into the future.