In Hong Kong, your feet need never touch the ground. But now, for the first time, a book can help you navigate the high-rise web of bridges, tunnels and lobbies that make up the city's fabric

In Hong Kong, it is possible to walk all day without ever having to set foot on the ground. In this super-dense metropolis, built on an implausible terrain of sheer-faced mountains and reclaimed land, you can go from your house to the office, via shops, stations and ferry terminals without once touching terra firma.

It is a city built on an intricate network of elevated bridges and submerged tunnels, aerial walkways and suspended passages. The platforms of transport hubs meld into labyrinthine malls, which in turn bleed into office lobbies. Branches of stairs and escalators continuously connect onwards and upwards, to the extent that you're never quite sure what altitude you might be at, how far from the street you have risen – or if, in fact, there was even a street to begin with.

This unique urban condition has now been mapped for the first time by a group of architects and academics, who have brought their findings together in Cities Without Ground: A Hong Kong Guidebook. The work of Adam Frampton, Jonathan D Solomon and Clara Wong, the book takes a systematic look at the layered topography of the city, drawing over 30 key areas in exploded axonometric diagrams to reveal the interweaving networks of pedestrian infrastructure.

A map shows the interconnecting levels of the Shun Tak Centre and Sheung Wan – a hub that connects trains, ferries, helicopters, buses and taxis, alongside a neighbourhood of dried seafood shops. Image: Oro Editions

The project claims to be "a manifesto for a new theory of urban form" and the authors argue that Hong Kong "demonstrates the viability and even robustness of public spaces that do not resemble a street or a square."

In such a city of artificial ground, the activities that usually happen in a park or civic square are instead displaced into the air-conditioned lobbies of shopping centres, or the shady undercrofts of office blocks. On Sundays, some of these zones are entirely taken over by armies of domestic workers on their day off, sitting in endless rows on blankets, chatting, eating and snoozing. In other areas, groups of retired men gather to show off their songbirds, while a nearby gaggle of children practise musical instruments.

The maps depict an impossibly elaborate web, with escalators, ramps and walkways stretching for miles in every direction, spreading like the vigorous root systems of an army of weeds. It is an unplanned, often illogical matrix, which is the result of piecemeal development – different links and stitches built by different parties over time according to their specific needs. It is, the authors write, "a result of a combination of top-down planning and bottom-up solutions, a unique collaboration between pragmatic thinking and comprehensive masterplanning."

The phenomenon began in the 1960s, when the Hongkong Land company, one of the main developers in the region, built an elevated walkway to connect a luxury hotel to the second storey of an adjacent shopping mall. An insignificant move, perhaps, but it in fact had the effect of changing the rentable values within the building: suddenly the mall's second floor units could be rented out for more than those at ground level. It entirely recalibrated the vertical logic of real estate value.

The government also caught on to this being a good way to move people around town without getting in the way of traffic, and so the elevated urban realm began to grow – beginning with transport hubs, but soon extending throughout the city.

West Kowloon … Hong Kong’s gateway to China, a multi-storey landscape with an aromatic garden and kids’ fun world. Image: Oro Editions

Drawn in a bold graphic style that is somewhere between Haynes construction manual and SimCity, the maps are annotated with some of the activities that occur across the many layers and levels of these pieces of infrastructure. The Shun Tak Centre and Sheung Wan – a hub that connects trains, ferries, helicopters, buses and taxis, alongside a neighbourhood of dried seafood shops – depicts a landscape where housewives haggle over preserved sausages, around the corner from a jockey club and fabric bazaar.

A map of the Olympic neighbourhood shows that even bedroom communities and back-office complexes are relentlessly connected, where an impatient private maths tutor and bored child practising the piano share two different levels of the same piece of an elevated interchange. Elsewhere, impromptu art exhibitions and political protests take place in shopping malls, pavements become salons or workshops, and covered bridges are transformed into restaurants and dance halls.

Although sometimes falling foul of the architect's tendency to fetishise the visual richness of exploded diagrams over the clarity of what they actually mean, the book represents a valuable piece of work. It captures this specific moment in time, and shows that these connecting stitches of routes and walkways not only aid connectivity, but provide the informal social arteries on which the city thrives.