Yongle removed all mention of his roasted relative from historical record and used all available means to establish his own righteousness. These often involved construction.

Like many a great dictator, he built on a scale designed to awe his subjects, to establish his legitimacy through sheer presence, and to persuade posterity of his right to rule. He built temples to ingratiate himself with heaven and to establish relationships with senior religious figures on Earth. He built with an innovative simplicity that sent Chinese architecture in a new direction, and which enabled him to put up halls rapidly and economically, but with an emphasis on using materials of the highest quality.

Six hundred years on, this often overlooked architec­tural legacy is being reassessed. Yongle built to communi­cate, and while there are fewer of his buildings remaining than is often claimed, there’s rather more to see in them than is commonly noted.

Yongle’s Beijing served as a metaphor for the emperor, says Aurelia Campbell, a professor of Asian art history at Boston College and author of What the Emperor Built (2020). The buildings of his new capital “had a sense of order and uniformity that communicated the message of a strong centralised power controlled by a capable moral ruler”, she writes.

Yongle is commonly connected with Beijing’s Forbidden City, where visitors are drawn straight to the vast spectacle of what is now called the Hall of Supreme Harmony – Yongle’s Hall of Revering Heaven. Its dizzyingly compli­cated bracket sets support the vast yellow sweep of a main roof and secondary eaves. Gaudy red-and-gold screens and pillars compete to dazzle while beams in green and blue feature hundreds of golden, writhing dragons.

It all fizzes and buzzes its way aloft, sitting with its two smaller but equally hubris-laden companions on a triple-layered carved marble terrace that lifts all three halls still closer to heaven.

Magnificent as it is, the Hall of Supreme Harmony visible today is not Yongle’s creation, and general claims that today’s Forbidden City is the world’s largest and best-preserved example of medieval architecture are not to be taken at face value, although visitors are often encouraged to think so. The burned-out hall was not even rebuilt in Yongle’s lifetime, but there’s much to be learned about him from it nonetheless.

The appearance of the hall and its construction methods were remembered when it was rebuilt 20 years later, writes Campbell, and it is known that some of the same craftsmen were involved. Working with a stock of 380,000 giant nanmu timbers left over from Yongle’s reign, they likely built a near-copy of his original.

Yongle would establish for the remainder of Chinese dynastic history that nanmu cedar was the pre-eminent wood with which to construct ceremonial halls, and he redefined what it meant for a building to be monumental.

The giant nanmu trunks, up to 1.3 metres in diameter, were found in remote valleys in the southwest, and brought to Beijing with epic difficulty.

“Once the timbers had floated to the larger rivers, they were bundled together in groups of eighty to form rafts, each of which was escorted by ten sailors and forty labourers to Beijing,” writes Campbell. “The rafts were first floated eastward down the Yangzi, then northward up the Grand Canal.”

It took between two and five years for the timbers to reach Beijing, and eyewitness reports say flotillas of these rafts supported a village’s worth of floating commerce: vegetable gardens, wine shops, butchers, tailors, rice vendors, and more.

The discovery of these trees, which enabled Yongle to build to new heights, was presented as a sign of heaven’s approval of his vast project. In 1407, one official dispatched to oversee timber collection in Sichuan province reported a miraculous event.

“One evening, without any human effort, a number of large felled trees on Mount Mahu emerged from the ravine and arrived at the river for transport.”

To immortalise the view that he was heaven-blessed,the emperor turned to construction, erecting a shrine and a now long-vanished stele with an inscription describing the supernatural event. Discovering this text in an ancient gazetteer was a highlight of Campbell’s research, and she found its Donald Trump-like qualities revealing.

“It says a lot about Yongle and how narcissistic he is,” she says on the phone from Boston, in the United States. And like any other dictator, “he turns around everything to himself. He just has to praise himself”.

In 1557, the Hall of Revering Heaven burned down again. The Jiajing emperor sent officials south­west to the forests, but the largest remaining trees were too far from watercourses to make transporting them feasible.

A passage in the Jiajing Veritable Records, Campbell tells us, recounts a debate between the emperor and his officials as to how to proceed.

“I am afraid that the former proportions certainly cannot be violated,” the emperor concludes, “therefore, we can just shrink [the scale] slightly.”

As one of his officials pointed out, to rebuild the hall’s marble-covered, triple-layered platform on a new scale would cost far more than the building that would sit on it, and might drag the project out for years.

So Yongle’s plinth remained intact with probably just the stone pillar bases moved to suit the building’s shrunken dimensions. But even then the nanmu available was still too small, and the now renamed Hall of Imperial Absolute had to have pillars manufactured by binding carefully sawn boards around a central slender trunkwith iron hoops.

The hall burned again in 1597, was rebuilt 30 years later, but reduced to rubble by an earthquake in 1679. The current hall was built in 1695 under the Qing dynasty’s Kangxi emperor, who renamed it the Hall of Supreme Harmony.

However, the pillar bases are spaced according to a Ming measuring system, rather than a Qing one. Yongle had ensured “bigger” would permanently be equated with “better”, and each new builder looked over his shoulder at the past, alluding to a now-vanished original. Also, the scale of Yongle’s plinth and surrounding courtyard demanded a building of a certain size.

When it came to finding materials, Kangxi faced a bigger dilemma than had Jiajing nearly 150 years earlier. When his officials reported difficulty in obtaining nanmu that were big enough, Kangxi compromised: “The roads in Sichuan are dangerous and difficult. The people are few and they have repeatedly undergone war. Their hardship and suffer­ing is already extreme. The gathering and transporting of timbers will certainly cause the exhaustion of the commoners.”

Although concern for the people smacks of Confucian piety, the hall was rebuilt using easier-to-obtain pine. But to create Yongle-scale pillars, the method of binding planks to a narrower trunk had to be used again.

Campbell remains sceptical of accounts about the original Hall of Revering Heaven’s size.

“There’s a lot of nationalistic pride associated with it,” she says. “You have textual references that describe the building being so large and a lot of Chinese scholars want to take that at face value. But I also feel you have to look at practicality and whether a building can be built that large or whether there was anything like that in Chinese history.” Which, she says, there just wasn’t.

Discovering the appearance and true scale of the original hall required some intriguing detective work.

Tradition has it that all capital builders followed instructions set out in the Kao Gong Ji, a 13th century insertion to a more ancient collection of documents called the Rites of Zhou. But Campbell disagrees.

“I don’t think Yongle really consulted classical texts at all,” she says. “I think he looked at his father’s capital and told his craftsmen to make the same thing.”

Hongwu had himself introduced novelties of layout, which Yongle copied wholesale to establish a strong symbolic connection to his father even as he moved the empire’s capital north, although he added to the palace a temple to Taoist martial deity Zhenwu, with whom he wished to be identified.

The epitaph of palace eunuch Ni Zhong documents his dispatch to Nanjing in 1417 to measure the palace halls there, the original blueprints having been lost. In research­ing measurements of the Hall of Supreme Harmony’s existing plinth and the dimensions of surviving Yongle-era halls Campbell was appropriately using the emperor’s own method to decide what he built and how he built it.

In recent years, Chinese PhD programmes in Ming architecture, such as that at Tianjin University, have produced fine architectural drawings of surviving Ming halls, several of which illustrate Campbell’s book.

These reveal the development in the early Ming of a new modular approach to construction, which meant that identical components could be prefabricated for multiple buildings. Yongle may have insisted on top-quality materi­als, but there was also a hint of Ikea-style standardisation of parts for quick assembly.

Evidence is found in Yongle-era towers over the palace’s Dong Hua and Shen Wu gates, and half a dozen concubines’ quarters and powder rooms for princesses. That these date from the Yongle era is suggested by the use of nanmu, of Ming decorative style, and in the lack of any record that a particular hall ever burned down.

It has been claimed that Beijing was built quickly, in just four years from 1416, but, in fact, an edict to find craftsmen was issued as early as 1406. Sections of the Grand Canal were dredged and an extension added to bring grain to feed the vast workforce and the timber required, most of which was harvested in 1406-7.

“At least a decade earlier,” Campbell points out in What the Emperor Built, “craftsmen and labourers had begun making the preparations for its construction by felling trees, quarrying stones, firing ceramic roof tiles, hauling bricks, pounding earthen foundations, and fabricating the parts of the timber-frame halls.” Yongle’s construction projects demonstrate his genius for organisation and planning.

Some idea of the true scale of the Hall of Revering Heaven is available just outside the Forbidden City’s main entrance, at the Ancestral Temple. Here, through a gate from Yongle’s time, stands one of the two oldest surviving Ming great halls, its super­struc­ture taller than that of the Kangxi-era Hall of Supreme Harmony, but on a lower platform.

The Ancestral Temple also burned down in the Jiajing reign, and its reconstruction in 1545 required 11,289 giant nanmu logs, using up the last accessible trunks of adequate size. Only the temple’s facade was altered, and otherwise the building remains as Yongle intended.

The largest surviving Yongle-era hall, closest in date to the Hall of Revering Heaven, is at Yongle’s tomb, the Chang Ling. Its Sacrificial Hall is the dominant building at the Ming tombs a short drive outside Beijing to the northwest.

On the same vast scale and with an equally important ceremonial purpose, it similarly stands on a triple-layer balustraded marble platform, with the same double-eaved roof in imperial yellow tile. Here the building perfectly fits its plinth, and the nine-bay design of the original remains intact, still impressively bulky, and gaudy, but simpler.

Like any good property developer, the emperor produced promotional materials, aiming to appease southern literati reluctant to make a move to the distant, unfamiliar and barbarian-haunted north. He took the artist Wang Fu with him on an inspec­tion tour in 1409, which resulted in a set of images of the Beijing district’s major sights, called “Eight Views of the Northern Capital”, completed in 1414.

In this volume, Yongle lauded both his own sagacity in choosing this site, and its merits as the location for a capital. After the destruction of his newly completed halls suggested that the heavens had a long memory for misdemeanours, and that the emperor was perhaps not quite so wise, Yongle issued an edict requiring “sincere words” of explanation from his highest-ranking officials, some of whom unwisely made full use of this right of reply.

One Zou Ji’s Memorial on the Hall of Revering Heaven Disaster decried the millions mobilised who could not tend their fields, the heavy taxation and the corruption.

His comments might describe Mao Zedong’s disastrous Great Leap Forward campaign of 1958-62: “At present a starving multitude in Shandong, Henan, Shanxi and Shaanxi eat nothing but tree bark, grass and whatever crumbs they can find. Others, in desperation, are forced to sell wives and children for their own survival.

“It is time to reflect and reform,” he added. “You should send all of those poor workers home so as to placate the anger of heaven. Let us return the capital to Nanjing and report to your father at his tomb about the reasons for the calamity.”

In a further reminder of Mao and other leaders since, critics who spoke out were not heard from again.

Tim Brook, a professor of history at Canada’s University of British Columbia and author of several histories of the Ming, such as The Confusions of Pleasure (1998) and The Troubled Empire (2010), has called Yongle the least Confucian of emperors, although he wrapped himself in the philosopher’s banner. “He browbeat his generation into accepting the fact that he had succeeded in the mandate of heaven,” says Brook on the phone from Victoria.

“He insisted on trying to create a scholarly record of himself as having been the legitimate heir of his father, Hongwu, of being a patron of scholarship, of doing all those things that Confucians said he should be doing.”

But it’s to the credit of Confucian philosophy, says Brook, that facts are seen as important. While for 150 years it might have been necessary to hold your tongue, the truth would eventually be told. During the 1572-1620 reign of the Wanli emperor, the historical record was corrected, and the existence of the Jianwen emperor acknowledged once more.

Nevertheless, Yongle is remembered for commissioning literary works, including an 11,095-volume encyclopedic com­pilation of knowledge, called the Yongle Dadian. He’s remembered for his diplomacy, sending arma­das out to the Indian Ocean and beyond to prod smaller states into sending envoys to bend the knee. And he’s remembered for his territorial expansion, which as China’s current rulers know well, wins approval at home. Yongle incorporated what are Guangxi, Guizhou and Yunnan provinces into China proper, and occupied what is now Vietnam.

His skill was in managing the northern border, playing competing khans off against one another and personally heading expeditions that kept his opponents defeated and divided, unable to reclaim the vast territory they had lost.

To be a good ruler is supposedly to be a Confucian one, but everyone likes a winner, and in the face of Yongle’s forceful rule, traditional Chinese historians often choose to look away from his authoritarian approach and its brutality. But not Brook.

“Tens of thousands of officials and their families were executed at the beginning of his reign – anyone who spoke out against him. And anyone who made even a whisper about the illegitimacy of his rule.”

But Brook agrees that Yongle’s relocation to Beijing was significant. On the 600th anniversary of the completion of Yongle’s Beijing, the emperor’s influence remains, and What the Emperor Built will make even those familiar with the city’s ancient buildings feel that while they may have looked, they perhaps did not entirely see.

“Yongle’s great monuments had important historical afterlives,” says Campbell, “continuing to shape the public perception of him well after his death. The contours of the city – its moat, walls, gates and main halls – endured for centuries and were forever afterward associated with the Yongle emperor.”