By Hannah Hennessy
In Machu Picchu
By late morning, the terraces at Machu Picchu - the jewel in the crown of Peruvian tourism - are heaving.
Peruvian children charge down the stairways at this majestic 15th Century Inca citadel. Exhausted backpackers take photographs of each other amid the misty ruins at the end of the gruelling four-day Inca Trail.
Some 400,000 arrived this year alone
After lunch, tours of wealthy American and British tourists, fresh from their journey on the new Orient Express train, gaze in awe at the site many have dreamt of visiting their entire lives.
But the site is becoming a battle ground between the United Nations cultural agency, which wants visitor numbers more than halved, and the Peruvian authorities, which are desperate to keep precious income from tourism flowing in.
Some 400,000 people will have visited Peru's most famous site this year, but Unesco says that is far too many.
The agency is worried that this citadel, thought to have been built by the great Inca ruler Pachacutec, is being damaged by increasing numbers of visitors.
Unesco says that if its warning goes unheeded, it will put Peru's only intact Inca ruin on its list of endangered sites.
But the Peruvian authorities are unperturbed by the rebuke - insisting there are no problems at the site.
"It's an exaggeration. They're trying to make the problem bigger than it is," said David Ugarte of the National Institute for Culture (INC), which oversees the day-to-day management of the site.
"We are working on a master plan for Machu Picchu at the moment."
Nestled between three sacred mountains, it was abandoned and forgotten before the Spanish invaded Peru.
The conquistadors, who destroyed most of Peru's other Inca sites, never found Machu Picchu.
Hidden under thick jungle for years, it was finally discovered in 1911 by the American explorer Hiram Bingham. Since then, it has been the major draw for tourists to Peru.
Author and photographer Max Milligan has lived in this region for 18 years and has seen the number of visitors to Machu Picchu grow. He sides with the INC in arguing that the site is not under threat.
"There are natural limits caused by its remoteness. You can only get here by walking the Inca Trail or by taking the train," he said.
"I don't think there are any more problems here than say at Angkor Wat in Cambodia or Stonehenge in Great Britain."
But for others, the edge is taken off their enjoyment by the sheer volume of tourists.
"It is quite unbelievable how they managed to build this all those years ago," said Evelyna de Beer, a Dutch tourist who had just finished the Inca Trail.
But she wishes the throngs would approach Macchu Picchu with more caution, and stop carelessly clambering over the site.
"Because otherwise we will have nothing in 20 years."