After the Hagia Sophia was converted back into a mosque in 2020, the entrance fees that had been charged when it was functioning as a museum were removed. The number of tourists that visited the building increased dramatically as a result, to the point where it was too crowded to properly lead tours, and there was a risk of damage to the historic site. 

In February, a second entrance was opened specifically for tourists, who once again are required to pay an entry fee, and are prohibited from visiting certain parts of the building, including the main floor under the dome. 

Trying to juggle the Hagia Sophia’s dual roles as a heritage tourism site and a functioning place of worship has led to a number of issues and conflicts, making it clear that it’s impossible to fulfill both roles perfectly at the same time.

https://www.lonelyplanet.com/news/istanbul-hagia-sophia-entry-rules