The world's biggest cities - Telegraph Defining the biggest cities by population in the world is surprisingly contentious. Here, we have ordered the cities according to the figures accepted by the United Nations, which takes into account extended urban areas - which is why, for example, New York City and Newark are bracketed together. Other accounts define a population as that belonging to the "city proper," without taking into account outlying suburbs (Shanghai is commonly cited as the most populous in this instance). In this list, we include 28 of the world's "megacities," all with a population in excess of 10 million. London, only just scrapes in. Jakarta, Indonesia Population: 10,176,000 million 36 Hours in Jakarta More on the United Nations population research Picture: Aleksandar Todorovic - Fotolia