Hagia Sophia was exposed to uncontrolled rainwater before it was cleaned, he said, adding that some four tons of rubble and mud were evacuated within the scope of the cleaning work carried out last year.
Noting that there are cellar structures two meters below the garden in front of the northwest facade, he said these are the infrastructure spaces of the original atrium of Hagia Sophia.
Most of the underground spaces of Hagia Sophia were built for plumbing and ventilation, he said, adding that it is difficult to cross the tunnels due to narrow spaces.
"Even breathing is not easy in these tunnels… When you think about the time they were built, we can understand how difficult it was for people to move in these dark places and it is not possible to use them for any other purpose," he added.