Tokyo is often cited as the most populous city in the world, with a metropolitan area population exceeding 37 million people.
Delhi has a rapidly growing population, currently estimated to be over 31 million people in the metropolitan area.
Shanghai is China's largest city by population, with a metropolitan area population of around 27 million people.
São Paulo is the largest city in the Southern Hemisphere, with a metropolitan population of approximately 22 million people.
Mexico City has a population of about 21 million people in its metropolitan area.