Many factors can be taken into consideration while comparing cities such as populations and area covered.In terms of population the largest city in the world is Tokyo-Yokohama with a population of over 35 million people and is still growing. The smallest city is called Hum which is located in the central part of Istria, North-west Croatia with a population of just 23 people. In terms of area Hulun Buir in China is the largest city in the world with an area of over 269,953 square kilometres and Vatican City is the smallest with an area of just 144 hectares.