PARIS (Reuters) - France’s Chartres cathedral, a vast 13th century building with 18 staff on the payroll, is a costly place to run, and the one million a year who normally come to see its famous blue stained-glass windows are an essential part of balancing the books. This year, however, the COVID-19 epidemic has slowed that flood of visitors to a trickle, throwing the UNESCO world heritage site into a financial crisis. “It is very difficult to survive,” Father Emmanuel Blondeau, rector of Notre-Dame de Chartres, told Reuters. The Catholic church nationally has lost 90 million euros ($109 million) in revenue this year, the Conference of French Bishops (CEF) estimates. It has furloughed hundreds of staff and may have to close or sell some places of worship next year, CEF’s finance head Ambroise Laurent told Reuters. While the state covers their upkeep, churches have to pay for their own staff, heating and lighting. That makes the crisis particularly acute for cathedrals, which feel obliged to stay open for the few believers who do come to pray - meaning high fixed costs that are no longer being covered by their usual revenue from collections, ceremonies and candle sales. At Chartres, candle sales alone would normally raise about 5,000 euros ($6,070) per week, but that has fallen to around 500 euros, said the rector. Before the epidemic, the cathedral employed 18 people. That is now down to 14, who alternate between working part-time and government furlough. After a dismal spring, visitors - including German and Austrian pilgrims - trickled back in the summer. But from Sept. 21, when Chartres and its region were declared a quarantine zone for COVID-19, they all but stopped coming. ADVERTISEMENT The Notre-Dame-du-Puy cathedral in Le Puy-en-Velay, central France, is another World Heritage site and a major stage on the Santiago de Compostela pilgrims’ route. It too has seen visitor numbers and income - mainly from candles and collections - plummet. Yet shutting its great wooden doors to save money is not an option. “This is a place of pilgrimage, we need to remain open, anyone should be able to come,” said its rector, Jean-Loic Ollu. ($1 = 0.8236 euros) Reporting by Geert De Clercq; editing by John Stonestreet