This week Peruvians are celebrating an event that most thought would never happen: a new and splendid museum is opening in Cusco to house the "treasures of Machu Picchu" which are finally returning to Peru after spending the last century in the Connecticut city of New Haven, where the American explorer Hiram Bingham took them after discovering the ruins in 1911.
As long ago as the 1950s Che Guevara was complaining, when he passed through Cusco on his motorbike, "Where can one admire or study the treasures of this indigenous city [Machu Picchu]? The answer is obvious: only in the museums of the United States."
By 2003, when Yale mounted a major exhibition of the artefacts in its home town of New Haven, the murmur of discontent had turned into a roar. Peru's First Lady, Eliane Karp, led the charge. She is a Belgian anthropologist married to the president at the time, Alejandro Toledo. Her passionate conviction that the artefacts belonged back in Peru – and a passionate need to show herself a patriot for her adopted country – made her a formidable adversary, as Yale discovered.
When I spoke to her a few weeks ago for a BBC Radio 4 documentary on Machu Picchu, she confirmed that Peru had threatened to ask Interpol to put Yale's President on the wanted list for theft, so that if he set foot outside the US he could be arrested. This "helped focus Yale's mind".
But it would be too easy to paint a simplistic picture of imperialista yanquis, as some Peruvians have dubbed both Hiram Bingham and Yale, who "stole" their national treasures. Bingham genuinely thought he was borrowing the artefacts for a limited period of research; he would have been horrified at how long they stayed in Yale. And the Andeanists at Yale who mounted the 2003 exhibition, Richard Burger and his wife Lucy Salazar, have done more to interpret Machu Picchu than anyone else. Their work has enabled us to see Bingham's fabled "Lost City of the Incas" not as some spiritual hideaway for the Virgins of the Sun, as he suggested, but as a more down-to-earth winter retreat for the Inca Emperor and his court: a "Camp David", in Richard Burger's words, "where they could relax, engage in sports and, you know, not see any lobbyists. And Machu Picchu, of course, was relatively close to Cusco just like Camp David is to Washington."
Burger and Salazar helped broker the final deal with Cusco University which allowed the artefacts to return – and no one is more relieved than Lucy Salazar. A Peruvian herself, she had been put in a difficult position when Yale was being seen in her native country as the villain of the piece.
I have known all the principal players in the battle over Machu Picchu for some time, and Salazar allowed The Independent an exclusive and early preview of what the new museum in Cusco will be like, as the last packing cases from the United States were still being opened to put the exhibition on the shelves.
The first and most striking impression, as she showed me around, is what a fabulous building the Peruvians have chosen to showcase the exhibition. The Casa Concha, just off Cusco's main square, was once the palace of Topa Inca, one of the most spectacularly successful of Inca Emperors. It was then occupied by a series of rich conquistadors who overlaid the Inca foundations with fine colonial decoration: above classical Inca walls and niches of well-cut granite ashlars are baroque murals of Spanish saints.
For decades many of the old Inca and colonial features had been stuccoed over – not that you were likely to see them. The building was closed to the public unless you had the misfortune to be arrested, because it was used as Cusco's police headquarters.
Now a full restoration has revealed its former glories. At the same time, archaeologists have dug into the foundations to discover both Inca burials and the original Inca floor, which lies some six feet below the surface.
And what of the artefacts themselves? 370 have been repatriated from Yale. Ironically many were impounded by Peruvian Customs who were not going to let national sentiment get in the way of bureaucratic procedure – which is why in the week before the museum's opening, some are only just arriving.
Having seen the 2003 exhibition in Yale, I already knew that there was little gold and silver of the sort that the Peruvian public fondly imagines. This is not a Tutankhamun display of riches. It is likely that the site was looted of many objects of metallic value long before Bingham arrived a century ago.
The real "treasure" of Machu Picchu that the museum reveals is how cosmopolitan and playful the court of the Inca Emperor was: on display are musicians' instruments, beautiful plates with bird's heads for handles, another pair with butterflies, broach pins, even a pair of ceramic dice. Visitors often approach Machu Picchu with such reverence that it is easy to forget that this was a place of pleasure, a royal estate. Bingham's rich haul from Yale is a testament to the argument that Machu Picchu was not primarily a sacred centre, but a more secular and courtly retreat for the Inca Emperor and his court away from the cares of state.
Yale's analysis of the bone chemistry from burials at the site has also shown that the population was an exceptionally diverse one, drawn from all over Peru, not just from the local population around Cusco: "more like New York than an isolated rural village in Peru, in terms of its cultural population," as Richard Burger has said. The metalwork and jewellery are equally diverse, a showcase of styles and indeed of materials: obsidian from near Ayacucho, tin from the far south in what is present-day Bolivia and pottery from right across their realm, as one would expect at a royal court.
We like to think of such ancient sites as being "authentic" homogenous examples of just one culture – and of Machu Picchu as a showcase for the classic "pure Inca" style – but in its heyday it would have been as cluttered with foreign objects as any London department store.
The image of Machu Picchu the new museum presents is of a small, courtly community of less than a thousand people, who came seasonally and for pleasure – much as modern tourists do. The display at Casa Concha may not be quite what New Age seekers after spiritual truth expect when they go to Machu Picchu – but as a revelation of its true purpose, it is superb, and the new museum is truly something both Peruvians and tourists can celebrate.
'Who found Machu Picchu?' is broadcast at 11am on Wednesday 5 October on BBC Radio 4
Area 62 times the size of Wales
Year of independence 1821
National animal Vicuna
Opening lines of national anthem Somos libres/Seámoslo siempre, seámoslo siempre ( We are free/Let us be always, let us always be)
Travel essentials: Peru
* There is no easy way to reach Cusco from Britain. Most travellers go via Lima, which can be reached via Madrid on Iberia (0870 609 0500; iberia.com); Sao Paulo, Toronto, Miami and Amsterdam are also possible transfer points. Alternatively, aim for La Paz in Bolivia (accessible via Miami on American Airlines), and travel overland from there.
* Hugh Thomson is leading a tour to Cusco and the Sacred Valley, including Machu Picchu, from 19 May to 3 June 2012 for Steppes Travel (01285 880 980; steppestravel.co.uk).
* Casa Concha, Calle Santa Catalina ( unsaac.edu.pe).
* Peru Tourist Board: 00 511 574 8000; peru.travel/en