When the lights go up next Saturday, after four years' preparation, Turandot's heart will finally yield to the Tartar Prince Calaf in precisely the historic setting envisaged by Puccini. Mehta, gesturing at the pavilions, said: "We don't need scenery. Just to see this, it inspires you."
But it took considerable effort to persuade the Ministry of Culture that staging the opera in the Forbidden City would be a good idea. "Five years ago, I would have said it was impossible because they kept on saying no," said Mehta.
Michael Ecker, executive producer from Opera on Original Site, the enthusiasts for staging operas in their authentic venues, said: "Zhang Yimou had to make a very detailed presentation of this project. They wanted to make sure it was a Chinese opera, a Chinese presentation."
And so it is. This is a Chinese Turandot, devoid of fake chinoiserie. Zhang (the Oscar-nominated director of Raise the Red Lantern) insisted that the $600,000 gold and red hand- embroidered silk costumes, the stylised make-up, the body language of the Western principal singers, and the movements of the 100 Chinese dancers must all be authentically Ming dynasty, in keeping with the architecture of the Forbidden City. Out went the existing Tang dynasty costumes.
This attention to detail does not come cheap. Apart from two performances for all-Chinese audiences when the tickets are cut-price, the cost of a seat is between $150 and $1,250 - even
more for anyone who also wants the 15-course post-performance banquet.
Mehta said: "A production like this costs a lot of money ... Although classical music in the Western world always loses money, we can't afford to lose money here."
Some 350 artists and technicians have been flown in from Florence, and there are three casts of principals for the nine performances, including Giovanna Casolla, Sharon Sweet and Audrey Slottler alternating in the title role. Pizza Hut and Kentucky Fried Chicken are operating food concessions, and the publicity material advises that "international companies will find this event an ideal ambience in which to entertain and extend their contacts to their Chinese business partners". Ordinary workers may have to settle for watching the televised performance.
The organisers are offering an event to remember. Below the long sloping, yellow-tiled roofs of the ancestral hall, and surrounded by the red walls of the Forbidden City, Zhang has recreated the imperial Ming court "as magnificent as the Forbidden City itself, to show the greatness of the great dynasty in China's ancient times". Four fake pavilions have been constructed to complete the set. In some scenes more than 1,000 people will be on the 270ft wide stage. And the cast includes some 260 soldiers as extras who "will participate in the performance both as mass performers and as guards", explained one newspaper.
So has the icy and vindictive Chinese Princess Turandot been toned down for China? "No," insisted Mehta. "In fact, some of it is quite bloodthirsty. Mr Zhang brings out the charts and shows the rules of beheading, that we've never seen before. It's quite pagan actually."
Puccini died in November 1924, just months after the Last Emperor was forced to leave the Forbidden City, and the final scenes of Turandot had to be completed by his former pupil, Franco Alfano. It is the opportunity to present Turandot in true Chinese staging which seems to have persuaded Peking to give the go-ahead.
Zhang Yu, at the China Performing Arts Agency, said: "For 70 years there have been a lot of Turandot productions presented to the world ... but most of these were from the point of view of Western people interpreting Oriental culture."
Just in case of any political upsets, such as the sudden decision by Shanghai in June to ban a Chinese opera troupe from performing in New York, the organisers have insurance against a last-minute cancellation by the authorities. The biggest threat, however, is probably the weather; in theory it does not rain in Peking in September, but that did not fail to stop part of the UN Women's Conference being a wash-out in 1995 when the heavens opened.
In the final weeks, the only controversy has been some disquiet among historians about using the Forbidden City as the setting. Xie Chensheng, a relic expert, said: "Cultural relics cannot be turned into stage props. There is no need to stage performances in such an important place."
There is already at least one firm convert to Italian opera. Zhang said: "From the first time I attended a rehearsal, I was amazed. The singers stood right beside me. When they started to sing, I'd never experienced anything like it. Their voices and the music were so beautiful."