Tucked away in the Peruvian Andes, the ancient Incan citadel of Machu Picchu has been historically difficult to reach. Formerly a refuge for the Incan elite in the 15th century and later a popular pilgrimage destination, Machu Picchu is now overrun with tourists, who typically fly into the single-runway airport in the nearby city of Cusco and then take a train or a multi-day hike to reach the UNESCO World Heritage Site.

To make Machu Picchu more accessible to tourism, the local government has started construction on a new international airport in Chinchero, an Incan town considered the gateway to the Sacred Valley.

Expected to be completed by 2023, the $5 billion Chinchero Cuzco International Airport has sparked outrage both locally and abroad over concerns that increased tourism to an already overcrowded site would degrade the area’s beauty and character—and lead to greater environmental destruction to the vulnerable archeological campus.

According to The Guardian, Machu Picchu’s visitors swelled to over 1.5 million in 2017—averaging approximately 5,000 people a day, a number that’s nearly double the 2,500-visitor cap recommended by UNESCO.

Nearly 50,000 people have signed a petition imploring the Peruvian president, Martin Vizcarra, to reconsider the project. “The airport planned to be built in Chinchero, Cusco, endangers the conservation of one of the most important historical and archaeological sites in the world,” says the Change.org petition. “An airport in the surroundings of the Sacred Valley will affect the integrity of a complex Inca landscape and will cause irreparable damage due to noise, traffic and uncontrolled urbanization.”

In an online statement, Rachel Williams, founder of Latin America travel company Viva Expeditions, expresses worry that “more day trippers or ‘tick box tourists’ could start visiting Machu Picchu, creating a theme park out of a sacred place.”

Yet, the government does not seem to be interested in changing its position. “This airport will be built as soon as possible because it’s very necessary for the city of Cusco,” Peru's finance minister, Carlos Oliva, told media last month. “There's a series of technical studies which support this airport's construction.”

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