Tehran (/tɛəˈræn, -ˈrɑːn, ˌteɪ-/; Persian: تهران Tehrân [tehˈɾɒːn]) is the largest city in Tehran Province and the capital of Iran. With a population of around 9 million in the city and 15 million in the larger metropolitan area of Greater Tehran, Tehran is the most populous city in Iran and Western Asia, and has the second-largest metropolitan area in the Middle East, after Cairo. It is ranked 24th in the world by metropolitan area population. The City Council declared October 6 Tehran Day in 2016, celebrating the day in 1907 when the city officially became the capital of Iran.