A big part of visiting the ancient Inca ruins of Machu Picchu in Peru is getting there: pilgrims leaving the city of Cusco either need to take a multi-day hike to the site high in the Andes mountains or ride a slow train through the Sacred Valley, absorbing the alpine landscape that remains largely unchanged since ancient times. But a controversial new way to reach the ruins may upend this; bulldozers have begun clearing land for a multi-billion-dollar international airport in Chinchero, just 20 minutes from the Sacred Valley.

Dan Collyns at The Guardian reports that locals, archaeologists and tour operators are petitioning the government to reconsider the project, which is planned to be completed by 2023.

“The airport will affect the integrity of a complex Inca landscape and will cause irreparable damage due to noise, traffic and uncontrolled urbanisation,” writes Natalia Majluf, a Peruvian art historian at Cambridge University, who is spearheading the petition.

The major concern around the Chinchero Cuzco International Airport is that the project will only add more strain to a cultural site that is already struggling to deal with growing crowds. Colleen Connolly at The Chicago Tribune reports that the Machu Picchu handles almost 6,000 people per day, more than double the 2,500-person cap recommended by the Unesco, the United Nations cultural organization. “The tourist impact is very grave,” Nelson Huaman Quispe, a guide with Machu Picchu Andes Tours, tells Connolly. “As there are a large quantity of tourists, you can't control them.” People are reportedly climbing on the structures, taking rocks as souvenirs, and leaving marks on the ancient stones.

Even tour operators, who are the most likely to benefit from the airport, are not all onboard with the project. In a press release, Rachel Williams, founder of Viva Expeditions, which specializes in travel to Latin America, says the airport will ruin the character of the area and decimate the economy of Cuzco. “Plane landings into the guts of the sacred valley is simply a bad idea. Air traffic in the area would create a lot of disturbance not only physically but the noise will shatter the peace degrading the whole sacred valley experience,” she writes. “More day trippers or ‘tick box tourists’ could start visiting Machu Picchu, creating a theme park out of a sacred place.”

Building a nearby airport to Machu Picchu has been floated since the 1970s, and local supporters point to the construction jobs and other possible benefits the project could bring, for instance, giving visitors to the site direct flights from Latin America and the U.S. The Cusco airport, where most tourists fly into, has one runway and can only accommodate smaller planes coming from Peru’s capital Lima, meaning all visitors need to make at least one stop. Cusco’s airport infrastructure is also maxed out, making additional capacity necessary, as Mark Rice, the author of Making Machu Picchu: The Politics of Tourism in Twentieth-Century Peru, tells Collyns; however, Rice cautions, putting an airport so close to the site would do a “lot of damage” to the area's “scenic beauty.”

Machu Picchu, which was designated a World Heritage Site in 1983, began seeing larger crowds after it was voted one of the “New Seven Wonders of the World” in an online poll in 2007, Connolly reports. Nearly every year since then, Unesco has recommended Machu Picchu be placed on its list of most endangered World Heritage Sites. So far, Peru has worked with the body to make changes to avoid the designation, including roping off certain areas, adding guards and implementing visitor caps. But the airport may finally push the historic site over the precipice.