As Hiram Bingham hacked his way through remote Andean cloudforests in search of a lost Inca citadel in 1911, little could the American adventurer have known of the tourism juggernaut that his archaeological expedition would unleash – or how it might threaten his breathtaking find.
Now, Peru is gearing up to mark the centenary of Bingham's rediscovery of Machu Picchu with a series of glitzy events on 6 and 7 July. Sponsored by Coca Cola, the festivities will include international broadcasts of a son-et-lumière show and a concert expected to feature the Spanish tenor José Carreras.
But many in the archaeological community are deeply worried about the pressures on Machu Picchu from the 2,000 visitors it receives every day and the rapid growth of over-priced hotels, tacky souvenir shops, fast-food restaurants and other unregulated infrastructure around the citadel and along the Sacred Valley that links it to Cusco, the former Inca capital.
"In 10 years' time, the valley will be like a giant amusement park, like Disneyland," warns Jose Canziani, an expert in the strategic development of archaeological sites and professor at Lima's Catholic University.
The World Heritage Committee of Unesco, the United Nations cultural organisation, agrees. In 2008, it voiced its "grave concern" regarding the mismanagement of Machu Picchu, and in 2009 expressed its frustration at Peru's refusal to allow the ruins to be placed on a list of endangered sites. The panel highlighted problems from the wearing away of the original stone paving to the increased risks of landslides caused by deforestation as a result of the chaotic construction boom.
The committee is due to report next month on Peru's progress. Anything less than a ringing endorsement could prove highly embarrassing for President Alan Garcia's administration.
The Peruvian authorities have made some headway. The government banned the helicopter overflights enjoyed by some of Machu Picchu's more affluent visitors. Yet problems persist. In January last year, landslides in Aguascalientes, the tourist trap at the base of the mountain on which Machu Picchu sits, killed five people and left several thousand sightseers stranded for days. Machu Picchu remained closed for three months. And there has been no response to the erosion of the original stone paving. Wooden walkways or a requirement for visitors to wear rubber-soled shoes are two obvious solutions, says Jeff Morgan, executive director of the Global Heritage Fund, a San Francisco-based group working to protect archaeological remains in the developing world, but there has been no word from the Machu Picchu research team run by Cusco's regional government.
Further down the Sacred Valley, tourist traffic over-runs Ollantaytambo, an Inca fortress that was the scene of one of the Andean empire's few military victories over the invading Spaniards. Buses clog the narrow, cobbled streets of the village.
"Peru has been selling this idea that we are this amazing tourist destination but the reality is that we are not attending adequately to our visitors," complains Joaquin Randall, the manager of El Albergue, the town's oldest hotel, founded in 1925.
Suggestions by Ricardo Vega Llona, the businessman presiding over the centenary celebrations, that more people should visit Machu Picchu have been met with alarm by conservationists, who argue tourist traffic needs to be directed to other sites. Peru has 100,000 identified sites of archaeological interest. But only 2,800 have been officially signposted and marketed as attractions, while as few as 200 are protected with barriers or personnel.
"Everyone wants to go to Machu Picchu but there are 25 other sites in Peru that are just as amazing," Mr Morgan told The Independent. Channelling visitors to these other sites would also better distribute the economic benefits of tourism in a country where nearly half of rural residents still do not get enough to eat.
Yet some of Peru's greatest ruins, such as the imposing mountain fortress of Kuelap in northern Peru, have no road access and require strenuous treks of several days.
Meanwhile, the directorate of archaeology in Peru's recently-founded Culture Ministry struggles with an annual budget of less than £1m and just 100 employees. According to Elias Mujica, a consultant on the development of archaeological sites, the directorate is "crippled" despite Peru's immense archaeological resources and the economic opportunity they provide.
"Just imagine it," sighs Hector Walde, head of the directorate, when it is pointed out that the equivalent agency in Mexico has around 2,500 staff working to protect Aztec, Maya and other ruins. The backlog of issues piled up in his inbox includes looting, uncontrolled urban development and inappropriate reconstruction by foreign archaeological teams.
Last month, authorities removed 4,500 tons of rubbish dumped by local communities inside the perimeter of the World Heritage Site Chan Chan, a spectacular pre-Inca adobe city on the Pacific coast. And farmers have been attempting to seize land at Caral, just north of Lima, a complex from 2,600BC and one of the Americas' oldest known inhabited sites.
One exception to the troubling picture is the Moche Route, a successful new tourist circuit on Peru's northern coast, linking ruins from the Moche people, famous for their lewd ceramics. The sites, including the giant Pyramids of the Sun and the Moon, are well conserved and local communities were involved in its strategic planning.
Yet even here there are serious problems, with unprotected Moche ruins providing one of two archaeological looting hotspots in Latin America. The other, in Guatemala, sees the smuggling of an estimated 1,000 Maya ceramics a month, with a market value of more than £6m. No one seems to have an equivalent figure for Peru although Mr Walde estimates there are around 25,000 people involved in the trafficking nationally, most of them impoverished locals who earn a pittance, while a handful of middlemen make millions. The margins are comparable to the drugs trade, with retail prices around 1,000 times greater than the amount paid to the looter.
"Looting has gone on for centuries. It is a tradition in Peru," Mr Walde says. "There is no awareness that looting tombs is prohibited. It is not socially censured."
The courts, meanwhile, lack teeth. Peruvian law provides for sentences of up to eight years for illegally trading artefacts but prosecutors are usually unable to prove a suspect was knowingly involved in ransacking a marked archaeological site.
For Bingham, his rediscovery of Machu Picchu heralded a triumphant return to America, where he eventually became a senator and, after his death, the model for the Indiana Jones movies. Yet the legacy of his momentous find is less clearcut for Peru. As the centenary celebrations get under way, a questionmark continues to hang over the government's ability to protect the archaeological riches many regard as a global as well as a national patrimony.
Cradle of civilisations
* The Inca empire, which started off as a tribe in what is now Peru and established a dominion that stretched from modern-day Chile to Colombia, actually only lasted 200 years yet was the culmination of millennia of civilisation in the Andean region. The diversity of cultures rivalled that of the Mediterranean basin.
* Cuzco was the capital of the Inca empire from which kings ruled. The empire was tied together by an extensive road system. Inca architecture is distinguished by the use of stones sculpted to fit without the use of mortar.
* Known as fearsome warriors, the Incas built their empire through both force and diplomacy. But it was destroyed when Spanish invaders, led by Francisco Pizarro, arrived in Peru in 1532. The Incas were unable to match the firepower of the Europeans, and the explorers also brought with them diseases such as smallpox that devastated the indigenous people.
* Peru is today littered with the stunning ruins of cultures that scholars know little about. Among the most notable are the Paracas people from the deserts of Peru's southern coast in about 500BC, who made dazzling textiles; the warlike Wari empire from the southern Peruvian Andes, from 500AD to 1000AD; the Moche, from 100AD to 800AD; and the Chachapoyas people of Peru's northern cloudforests, who left a mausoleum full of mummies chiselled into a cliffside.
* The Incas worshiped a number of gods. The most important of these was Inti, the sun god. According to Inca belief, the Inca emperors descended from him.
Other tourist sites at risk
Angkor Wat, Cambodia
Illegal pumps withdrawing millions of litres of groundwater every day from beneath the city of Siem Reap may threaten the stability of the nearby ancient temples of Angkor Wat, Unesco says. Growing numbers of tourist hotels are blamed for such high water demand. More than 800,000 people visited Angkor Wat in the first nine months of 2010 – 24 per cent more than in the same period the year before.
The 2,000-year-old House of the Gladiators in this ancient Roman city collapsed last November, pictured right, prompting an outcry from historians who fear the government is neglecting Italy's priceless national treasures. Three chunks of mortar also fell off Rome's Coliseum in May last year.
Everest Base Camp, Nepal
Refuse, medical waste and an ever growing number of tourist cafés are blamed for creating the "highest junkyard in the world" at the popular trekking destination. Conservationists continue to call for a temporary closure of the site in an attempt to reduce visitor numbers and their negative environmental impact.
Grand Canyon, Arizona, US
Noisy air tours and pollution are putting the Grand Canyon National Park at "grave risk", according to a report released last year. Every year, more than 400,000 tourists fly above the canyon in helicopters and light aircraft, which are blamed for ruining the park's natural soundscape.
Great Barrier Reef, Australia
The world's largest reef system, housing over 400 species of coral and 2,000 species of fish, is threatened by a combination of climate change, rising sea levels and shipping. Last year the Chinese trawler Shen Neng 1 destroyed over 3km of coral when it ran aground.