The second-largest metropolis in the Arab world after Cairo, Baghdad serves as the nation of Iraq's capital. It is situated on the Tigris River in the centre of ancient Mesopotamia, some 330 miles (530 km) from the headwaters of the Persian Gulf. The city was established in 762 to serve as the capital of the Abbasid dynasty of caliphs, and for the next 500 years, it was both one of the greatest cities in the world and the most prominent cultural hub of Arab and Islamic civilization. With connections by road and rail to other significant cities in Iraq and its neighbours, Baghdad serves as a major transportation hub. A major airport is also located in the city. Baghdad is a significant industrial hub with plants making machinery, food, chemicals, and textiles. The city serves as a significant hub for trade and business. With a population of over 7 million people from all over the world and Iraq, Baghdad is a multicultural city. Although Arabic is the city's official language, Kurdish, Turkish, and Persian are also widely spoken. The majority religion in Baghdad is Islam, but there are sizeable Christian, Jewish, and other religious minorities as well. Both Baghdad's history and culture are vibrant. The city is home to numerous historical landmarks, such as the Ctesiphon ruins, the Abbasid Palace, and the Great Mosque of al-Mustansiriyah. Traditional markets in Baghdad include the Al-Ghazliyah Market and the Al-Kharkh Market. In its long history, Baghdad has endured many things, including battles, invasions, and natural disasters. However, the city has always recovered and is still a thriving and significant hub of trade and culture in the Middle East.