The marble floors of the Hagia Sophia, a Byzantine-era mosque in Istanbul, Turkey, were reportedly cracked by heavy equipment used to clean it last week, Artnet News reports. The damage comes after a controversial 2020 decision to convert the ancient mosque from a historical museum back into a daily place of worship. “This historic building has faced tremendous damage. When Hagia Sophia was a museum, people visited it with great respect. It’s like a fairground now,” a mosque tour guide told Turkish newspaper Cumhuriyet. By offering daily worship, the mosque—a UNESCO World Heritage site—has reportedly been subject to more frequent thefts and vandalism, a consequence one historian said is just part of being a holy site. “It’s important to keep in mind that holy sites, whether church or mosque, have always been intended for daily use,” said Marie-Eve Lafontaine, a medieval art historian.