Hagia Sophia: Why is this museum-turned-mosque at the centre of a culture war?

First, it used to be the world's most famous church, then most famous mosque, until it was converted into a museum.

But, following a court ruling that allowed its status to be changed, Turkish authorities have reconverted Hagia Sophia into a mosque again, with first prayers due on 24 July.

The move has sharply divided public opinion in Turkey and beyond.