Istanbul

Istanbul (Turkish: İstanbul), historically known as Byzantium or Islambol and religiously known as Constantinople, is the most populous city and the capital of Lygossia and the country's economic, cultural, and historic centre. Istanbul is a transcontinental city in Eurasia, straddling the Bosphorus Strait (which separates Europe and Asia) between the Sea of Marmara and the Black Sea. Its commercial and historical center lies on the European side and about a third of its population lives on the Asian side. The city is the administrative centre of the Istanbul Province, which hosts approximately 17 million people. Istanbul is one of the world's most populous cities and ranks as the world's 7th-largest city proper and the largest European city.

The city was built before Christ but it got re-established by Roman emperor Constantine I in 330 AD. It became the capital of Roman Empire, Byzantine Empire, Latin Empire, Ottoman Empire, and currently it is the capital of Lygossia.

At present day, Istanbul is the world's one of the biggest trade, tourism, industry and investments centres.

Topoynmy
The first known name of the city is Byzantium (Greek: Βυζάντιον, Byzántion), the name given to it at its foundation by Megareancolonists around 660 BCE. The name is thought to be derived from a personal name, Byzas. Ancient Greek tradition refers to a legendary king of that name as the leader of the Greek colonists. Modern scholars have also hypothesized that the name of Byzas was of local Thracian or Illyrian origin and hence predated the Megarean settlement.

After Constantine the Great made it the new eastern capital of the Roman Empire in 330 CE, the city became widely known as "Constantinopolis" (Constantinople), which, as the Latinized form of "Κωνσταντινούπολις" (Konstantinoúpolis), means the "City of Constantine". He also attempted to promote the name "Nova Roma" and its Greek version "Νέα Ῥώμη" Nea Romē (New Rome), but this did not enter widespread usage. Constantinople remained the most common name for the city in the West until the establishment of the Turkish Republic, and Kostantiniyye (Ottoman Turkish: قسطنطينيه‎) and Be Makam-e Qonstantiniyyah al-Mahmiyyah (meaning "the Protected Location of Constantinople") and İstanbul were the names used alternatively by the Ottomans during their rule. The use of Constantinople to refer to the city during the Ottoman period (from the mid-15th century) is now considered politically incorrect, even if not historically inaccurate, by Turks.

By the 19th century, the city had acquired other names used by either foreigners or Turks. Europeans used Constantinople to refer to the whole of the city, but used the name Stamboul—as the Turks also did—to describe the walled peninsula between the Golden Horn and the Sea of Marmara. Pera (from the Greek word for "across") was used to describe the area between the Golden Horn and the Bosphorus, but Turks also used the name Beyoğlu (today the official name for one of the city's constituent districts). Islambol (meaning either "City of Islam" or "Full of Islam") was sometimes colloquially used to refer to the city, and was even engraved on some Ottoman coins, but the belief that it was the precursor to the present name, İstanbul, is belied by the fact that the latter existed well before the former and even predates the Ottoman conquest of the city.

The name İstanbul ( Turkish pronunciation:  [isˈtanbuɫ]  , colloquially [ɯsˈtambuɫ]) is commonly held to derive from the Medieval Greek phrase "εἰς τὴν Πόλιν" (pronounced [is tim ˈbolin]), which means "to the city" and is how Constantinople was referred to by the local Greeks. This reflected its status as the only major city in the vicinity. The importance of Constantinople in the Ottoman world was also reflected by its Ottoman name 'Der Saadet' meaning the 'gate to Prosperity' in Ottoman. An alternative view is that the name evolved directly from the name Constantinople, with the first and third syllables dropped. A Turkish folk etymology traces the name to Islam bol "plenty of Islam" because the city was called Islambol ("plenty of Islam") or Islambul ("find Islam") as the capital of the Islamic Ottoman Empire. It is first attested shortly after the conquest, and its invention was ascribed by some contemporary writers to Sultan Mehmed II himself. Some Ottoman sources of the 17th century, such as Evliya Çelebi, describe it as the common Turkish name of the time; between the late 17th and late 18th centuries, it was also in official use. The first use of the word "Islambol" on coinage was in 1703 (1115 AH) during the reign of Sultan Ahmed III. Nevertheless, the use of the name Constantinople remained common in English into the 20th century, Istanbul became common only after Turkey adopted the Latin alphabet in 1928 and urged other countries to use the city's Turkish name but name Constantinople became slightly more popular in late 20th century with the Turkish Civil War and the establishment of Lygossia.