This picture taken on May 26, 2021 shows a view of the clocktower of the 19th-century Ottoman mosque of Mohamed Ali at the Cairo Citadel in the Egyptian capital. AFP

Conservation workmen restore the ceiling of the ablution fountain of the courtyard of the 19th-century Ottoman mosque of Mohamed Ali at the Cairo Citadel in the Egyptian capital on May 26, 2021. AFP

This picture taken on May 26, 2021 shows a view of the interior of the 19th-century Ottoman mosque of Mohamed Ali at the Cairo Citadel in the Egyptian capital. AFP

This picture taken on May 26, 2021 shows a view of the Baroque-styled ceiling of the main dome of the 19th-century Ottoman mosque of Mohamed Ali at the Cairo Citadel in the Egyptian capital, displaying the names of Islam's first four Caliphs on its corners, chronologically: (counter-clockwise from L) Abu Bakr, Omar, Othman, and Ali. AFP

This picture taken on May 26, 2021 shows a view of the Baroque-styled ceiling of the main dome of the 19th-century Ottoman mosque of Mohamed Ali at the Cairo Citadel in the Egyptian capital, displaying the names of Islam's first four Caliphs on its corners. AFP