Capital of Iran; population (2006) 7,797,500. The city produces over half of the country's manufactured goods, and industries include textiles, chemicals, pottery, electrical equipment, oil refining, vehicle assembly, engineering, and tobacco and sugar processing. It is built at an average altitude of 1,220 m/3,937 ft on a slope running south from the Elburz Mountains.
Tehran was founded in the 12th century and made the capital in 1788 by Muhammad Shah. Much of the city was rebuilt in the 1920s and 1930s. Landmarks include the Sepahsolar Mosque and library; the Gulistan Palace (the former royal residence); the Iran Bastan Museum; the Shahyad Tower, a symbol of modern Iran; the Borj-e azadi monument commemorating the 2,500th anniversary of the Persian Empire; and the tomb of Ayatollah Khomeini.
Formerly a suburb of the ancient city of Rey, Tehran became the capital in 1785 under the Qajar dynasty and expanded steadily in the 19th century. After the accession of Riza Shah Pahlavi (1925–41) the city was replanned and largely rebuilt, the walls demolished, and new avenues cut through residential quarters. The public buildings of the time, such as the university (founded 1935), employed Achaemenian or Sassanian styles for their exteriors. Modern Tehran exhibits marked internal differences; the southernmost part, the poorest, is a reception area for migrants from all over Iran and is socially the most conservative; further north, are the bazaar and many of the ministry buildings, while further north still the 19th-century once-wealthier suburbs, with leafy avenues and older buildings, have most of the foreign embassies. The modern central business district is in Takhte Jamshid and Firdausi avenues. After World War II there was rapid residential expansion north from here towards Shemiran, much of it in the form of four-storey apartment blocks. On the lower foothills of Tochal, the peak (3,800 m/12,467 ft) dominates the northern skyline. As the capital and largest city, Tehran is the seat of all the ministries, and much of Iran's industrial development is concentrated here. Tehran is also a major centre of higher education, and educational institutions include the Iran University of Science and Technology (1928) and the University of Tehran (1932).