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Explore the Hagia Sophia. Built by the Romans 1,500 years ago, it was the biggest church in the world.
No expense was spared: coloured marble from around the Roman Empire and nearly 10,000 square meters of gold mosaic. In 1453, the Hagia Sophia was turned into a mosque after Ottoman Turks conquered the city.
Now a museum, it has survived earthquakes, sieges and the rise and fall of empires.
Yet Hagia Sophia still stands, the ancient jewel in the crown of Istanbul.
Watch Ancient Invisible Cities on the BBC: https://bbc.in/2oFxiHi
Ancient Invisible Cities | Series 1 Episode 1 | BBC