As we've discovered there are many things that define a city and probably no one answer to "what defines at city?" is correct.
Generally a city is classed as an urban settlement or area. Some cities have formed as a result of the industrial revolution. There are many cities in the world, each with their very own unique culture and infrastructure.
It can be a challenging task to travel to and photograph a city, especially cities you've never been to. With their high speed highways and often complicated layouts, sometimes it is best to use either public transport or a taxi service.
The following selection of pictures of cities were taken from around the globe.
