Gli died at a veterinary clinic in Istanbul's Levent district where he was receiving treatment since September 24.
Gli, the cross-eyed adorable cat that had been living in Istanbul's Hagia Sophia mosque, has passed away at the age of 16.
The world-famous feline who made the Hagia Sophia her own is now part of the history of the iconic mosque.
"Hagia Sophia's cat Gli, who was being treated at a private veterinary clinic [Istanbul's] Levent [district] since September 24, unfortunately passed away due to her old age," Ali Yerlikaya, mayor of the Turkish metropolis, said on Twitter.
"We will never forget you, Gli," said Yerlikaya, posting a photograph of the cat, saying he was “deeply saddened.”
Earlier this year, as Hagia Sophia transitioned from a museum back to a mosque, Gli was unaffected by the hubbub. The architectural treasure was her home always, a point officials were quick to confirm.
Friday prayers July 24 in Hagia Sophia marked the first Muslim acts of worship there in 86 years.
Hagia Sophia served as a church for 916 years until the conquest of Istanbul, and a mosque from 1453 to 1934 – nearly 500 years – and most recently as a museum for 86 years.
And for the last several years, it served as a home to Gli, who will not be forgotten in the stately structure.