Hagia Sophia in Istanbul is one of the most architecturally significant monuments ever built, completed in 537 CE under Byzantine emperor Justinian as the largest cathedral in the world for nearly a millennium. For travellers asking Istanbul in which country, it stands in Turkey, at the crossroads of Europe and Asia, shaping the identity of a city whose Istanbul population now exceeds 16 million. Its 31 metre central dome was an engineering marvel unmatched until the Renaissance. Following the 1453 Ottoman conquest, the structure became a mosque with four minarets and monumental Islamic calligraphic medallions. In 1934 it was secularised into a museum, and in 2020 reconverted into an active mosque, though non Muslim visitors may enter outside prayer hours, so checking Istanbul time is essential. Inside, shimmering gold mosaics such as the Deësis and Empress Zoe panels coexist with Ottoman roundels bearing the names of Allah, Muhammad and the first caliphs. Recognised as a UNESCO World Heritage Site in 1985, it remains a highlight for anyone arriving via Istanbul Airport and exploring the historic peninsula before sampling Istanbul food at a nearby Istanbul restaurant.

What makes this place special

The 31 metre dome, carried on pendentives, was the largest of its age. Forty windows at its base flood the interior with light that early Byzantine worshippers described as heavenly.

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In the upper south gallery, the 13th century Deësis mosaic depicts Christ flanked by the Virgin Mary and John the Baptist, regarded as the finest surviving example of late Byzantine mosaic artistry.