In the depths of Beijing’s Planning Exhibition Hall, a big grey hangar that squats in the corner of Tiananmen Square, stands a scale model of the city. It is an endless field of tiny wooden and perspex blocks, low-rise courtyards huddled cheek by jowl with a motley jumble of towers, expanding ever outwards in concentric rings.

To attempt to build a model of China’s 22-million strong capital is a Sisyphean endeavour. This carpet of miniature rooftops is hopelessly incapable of keeping up with the city’s relentless pace of change, the exhibition hall too small to ever contain a megalopolis so sprawling that it is currently building its seventh ring road, an orbital loop that will run for almost 1,000km in circumference.

But the model’s bird’s-eye view exposes something that is illegible from the ground: the rigid order that underlies the rambling sprawl. A rhythm of axes, grids and symmetrical walled compounds emerges from the chaos, pointing to the fact that this seemingly incoherent metropolis is in fact the carefully structured product of one of the earliest planning documents in history.

The first thing you notice is the monumental fissure that slices north-south through the city, as if the urban grain had been severed by a great tectonic rupture. It is an axis that runs for more than 20km, shooting out like a laser beam meridian line from the walls of the Forbidden City, the palatial compound that lies at the centre of it all.

The 180-acre imperial palace appears to send ripples through the surrounding urban grain like a rock thrown into a pond, forming the successive layers of ring-roads. Its rhythm of symmetrical walled courtyards seems to structure the layout of the entire city, from the scale of blocks, to streets, to individual homes.

The effect is no accident: Beijing was conceived as a diagram of an organised, harmonious society, designed to bind the citizens together in bricks and mortar under the supreme rule of the emperor. It was to be an expression of absolute power like no other city in the world.

Founded more than 3,000 years ago as the city of Ji, Beijing’s present urban form was established in the early Ming dynasty (1368-1644), when the Yongle emperor moved the imperial capital here from Nanjing.

In establishing the fundamental layout of the new capital, the Ming reached for a suitably weighty touchstone, drawing on the teachings of the Kaogong Ji (roughly translated as “regulations of construction”), a text dating from the fifth century BC; part of the Rites of Zhou, an ancient Confucian manual of bureaucracy and organisational theory.

“It was a means of legitimising their rule,” says Toby Lincoln, lecturer in Chinese Urban History at the University of Leicester. “By explicitly drawing on this ancient manual of rites, their new capital city used divine numerology and ritual to express the power of the ruling elite in physical space.”

As one of the oldest examples of urban planning guidance in the world, the Kaogong Ji covers everything from how to determine north-south orientation when planning a new city (stick a pole in the ground and watch its shadow), to dictating the specific dimensions for local, regional and national capitals.

It states that the national capital should be “a square with sides of nine li” (a traditional Chinese unit of measurement equivalent to around 500 metres), with “each side having three gateways”. Inscribed within this square, it stipulates that there must be “nine avenues running north-south and nine running east-west, each of the former being nine chariot tracks wide” – a principle that perhaps set the precedent for the scale of modern-day Beijing’s agoraphobia-inducing highways.