When Istanbul chose a new mayor in March, Turkey's president described the vote as a matter of national survival.

But the ruling party's candidate was narrowly defeated and the new mayor, Ekrem Imamoglu, took office.

After a successful court challenge, the election was annulled and a rerun declared. Turks are now facing a dramatic second vote on Sunday.

Presenter: Beril Akman

Camera: Ilgin Karlidag

Editing: Suniti Singh

Video producers: Paul Brown and Pinar Ersoy