Why was Istanbul called 'Istanbul' and by who?

After the city fell to the Turks in 1453 it was still called Contantinople which became Kostantiniyye in Turkish and al-Qusṭanṭiniyah in Arabic, though in some contexts and titles the Turkish administration also referred to it as İstanbul from the Greek phrase "in the city". read more

İstanbul was the common name for the city in normal speech in Turkish even before the conquest of 1453, but in official use by the Ottoman authorities other names Names other than استانبول (İstanbul) had become obsolete in the Turkish language during the late Ottoman/early republican periods. read more

İstanbul was the common name for the city in normal speech in Turkish even before the conquest of 1453, [citation needed] but in official use by the Ottoman authorities other names, such as Kostantiniyye, were preferred in certain contexts. read more

Istanbul (UK: / ˌ ɪ s t æ n ˈ b ʊ l /, /-ˈ b uː l / or US: /-s t ɑː n-/ or / ˈ ɪ s t ən b ʊ l /; Turkish: İstanbul [isˈtanbuɫ] ( listen)), historically known as Constantinople and Byzantium, is the most populous city in Turkey and the country's economic, cultural, and historic center. read more