The world's most famous cities are also some of its biggest – from Tokyo to New York.
But there is one city that's so astonishingly vast that it's bigger than Austria and has a population of 32 million people and you've probably never even heard of it.
The Chinese “mega city” of Chongqing is located in South Western China and has an astonishing story – and is gaining fame thanks to viral TikTok clips.
YouTuber PPPeter produced a video on it called The Biggest City on Earth You've Never Heard Of – that is also known as China's Cyberpunk City.
He explained: “The story of this Chinese mega city starts and also kind of ends in 1997. Back then Chongqing was just a big city somewhere in South Western China.
“To boost the economy and make administration smoother Chinese government added three districts of Fuling, Wanxian and Quanjiang to Chongqing.
“This step made Chongqing the biggest city proper in the world with a population of 32,000,000 people and the area of 82,403km2, which is about the size of Austria.
“Nowadays certain areas of the city are so densely populated that original solutions to urban planning had to be made.”
And the planning solutions are just eye-popping – with the whole city being built on a number of different levels that look so much like ground level people get confused which floor they are on.
Chongqing local Jackson shared his day in the life of him getting to work in the fourth largest city in China on TikTok.
His daily journey involves elevators, subways without once so much as touching the ground floor. There are multi-level highways and a metro system even tunnels through residential buildings which are built on the side of hills.
He said in one clip: “The train casually goes through a residential building and here it goes through another residential building, because why not?”.
When Jackson arrives in the city square he asks his viewers that he “must be on solid ground at last, right?”. But in fact he's talking over the ledge of the square and revealed he's “on the 22nd floor of my office building,” reports MailOnline.
As Jackson walks to another edge he shows a terrifying shot of the busy roads below the office building.