Turkish treasure Hagia Sophia restoration aims to shield structure from earthquakes

Standing beneath the stone archways, grand murals and filigree lamps of the Hagia Sophia, the architect Hasan Firat Diker reflects on his vocation: the protection of a fragile structure that is Turkey's grandest mosque and perhaps its most contentious building.

- Ruth Michaelson

He is overseeing some of the most intense restoration and preservation works in the Hagia Sophia's nearly 1,500-year history, including efforts to strengthen its grand central dome and protect it from earthquakes.

"We are not just responsible for this building but to the entire world public," Diker said, gesturing at the crowds of visitors kneeling on the plush turquoise carpets or gazing at the murals of feathered seraphim.

He pointed up at the gold mosaic and blue mural interior of the main dome, which he described as one of the many "unsolved problems" of the Hagia Sophia's design.

The imposing structure, built in 537 under the Byzantine (eastern Roman) empire, is visibly uneven in places, in particular the grand dome, which for hundreds of years has sat atop four columns of different dimensions.

The entire building is a patchwork of repairs after the collapse of the original dome in an earthquake in 558, plus several half-domes in later tremors.

The Hagia Sophia still bears features from when it was one of the world's grandest cathedrals before its conversion into a mosque after the Ottoman conquest in 1453 of what was then Constantinople.

Transformed into a museum under the Turkish republic in 1935, it was reclassified as a mosque five years ago.