Short answers, pulled from the story.
Istanbul straddles the Bosphorus strait in northwestern Turkey, which divides it between Europe and Asia. About two-thirds of its more than 15 million residents live on the European side and the rest in Asia.
Istanbul served as the capital of the Roman Empire from 330 to 395, the Eastern Roman or Byzantine Empire from 395 to 1204 and again from 1261 to 1453, the Latin Empire from 1204 to 1261, and the Ottoman Empire from 1453 to 1922.
The name was officially changed from Constantinople to Istanbul on the 28th of March 1930 under the Postal Services Law. Constantinople had been in use for 1600 years, and the same law also renamed Angora as Ankara and Smyrna as Izmir.
Sultan Mehmed II, known as "the Conqueror," captured Constantinople on the 29th of May 1453 after a 55-day siege. The last Roman emperor, Constantine XI, was killed, and Mehmed declared the city the new capital of the Ottoman Empire.
The first known name of the city was Byzantium, given by Megarian colonists around 657 BCE. It was later refounded as Constantinople by Constantine the Great in 324 CE, who had initially called it New Rome.
Istanbul lies close to the North Anatolian Fault, which is locked just south of the city under the Sea of Marmara. This fault caused earthquakes in 1766 and 1894, and a quake of at least magnitude 7.0 is considered very likely in the 21st century.
Istanbul accounts for about thirty percent of Turkey's economy, and its productivity is 110 percent higher than the national average. In 2018 its GDP adjusted by purchasing power stood at 537.507 billion U.S. dollars.