Australia’s population clock is, according to the Australian Bureau of Statistics, steadily ticking away at an overall total population increase of one person every 1 minute and 23 seconds. It’s set to tick over to 25 million around 11pm tonight.

Many are debating what the ideal population is for a country like Australia. But because most of this population growth is concentrated in our big cities, perhaps we should be thinking less about that and more about the ideal size of a city. Historically, there have been many theories on what this would be.