Chongqing an urban phenomenon of verticality in China

This megacity is like Hong Kong on steroids - a vertically sprawling, astonishing urban phenomenon that can only be understood in three dimensions.

Google Maps can be unreliable at the best of times when you're travelling in China, but in the southern megacity of Chongqing, a map of any kind turns out to be almost entirely useless. Built across a series of impossibly steep mountainsides and vertiginous valleys at the dramatic confluence of the Yangtze and Jialing Rivers, it is an astonishing urban phenomenon to behold - a vertically sprawling city that can only be understood in three dimensions.

It is a place where neighbourhoods cling to cliffs, connected by elevated roads 20 storeys up in the air. Metro lines emerge from tunnels through the mountains, only to plunge straight through the middle of residential skyscrapers, which themselves sprout improbably from the sheer slopes. Something that looks close by on the map can turn out to be tens of storeys above or below you. And getting there usually makes for an exhilarating journey.

I first found myself in Chongqing 10 years ago, almost by accident, after my first attempt to enter North Korea was abruptly quashed when Kim Jong Un decided to close the borders overnight, because of his fears that foreigners might bring in Ebola. Stranded in Beijing with time to kill, a photographer friend recommended we head south to Chongqing. "It's like Hong Kong on steroids," was enough to convince me.

Nothing prepares you for the multi-level madness of this sprawling metropolitan region of 32 million people. Hong Kong might be known for its elevated walkways and urban escalators that zigzag up its steep slopes, but Chongqing takes this 3D cityscape to a whole new level. To get to places that looked like a couple of blocks away, I found myself taking steep staircases that led to underground escalators, then across walkways to lifts that ferried me up the side of a cliff. Cable cars swooshed past outdoor plazas, where what I thought was the ground level turned out to be the roof terrace of an office block, which plunged 30 storeys down into the valley below.

The experience of navigating the city felt like being thrust into a cross between the movie Inception and a game of snakes and ladders. In the end, I gave up on trying to navigate, and let this gloriously chaotic place swallow me into its concrete ravines.

I returned to the city last year, only to find that these infrastructural, topographical quirks have now become a phenomenally popular tourist attraction, chiefly among domestic Chinese tourists. "Best 'daka' point," declared a sign in Mandarin in the window of the residential tower at Liziba station, where the metro line shoots through the eighth storey of the block. Daka literally means "punching the card", as in clocking in and out of work, but it has become a millennial term for ticking sites off your travel bucket list - by taking a photo and posting it to social media, to show you were there.

Countless TikTok accounts now celebrate the vertical madness of Chongqing, with people recording their surreal daily commutes - Sisyphean trials of endless stairs that have the air of a Jacques Tati film. Photographer and tour guide Jackson Lu's commute has had more than 37m views. He begins his day leaving his 18-storey apartment (no elevator), reaching the ground floor at the 12th storey, where he walks across a bridge and on to the subway, a rollercoaster ride which swooshes through two residential buildings, before arriving at the city square - which turns out to be on the 22nd floor of his office.

The bus ride home is another dizzying hymn to civil engineering, looping around an elevated interchange in the clouds. It's just another ordinary day in this thrilling, bewildering megalopolis.