Tehrān, also spelled Teheran, the capital city of Iran and the centre of the province (ostān) of Tehrān, located in north-central Iran at the foot of the Elburz mountain range. Since its establishment as the capital city by Āghā Moḥammad Khān more than 200 years ago, Tehrān has grown from a small city to a major metropolis: situated in an urban region of 14 million inhabitants, Tehrān is Iran’s largest city and one of the most populous cities of the world. Area city, 270 square miles (707 square km). Pop. (2016) city, 8,693,706.With a dramatic topography reflective of its proximity to the highest peak in the country, Tehrān is Iran’s gateway to the outside world. Tehrān’s image abroad was strongly influenced by the Iranian Revolution of the late 1970s. In the last two decades of the 20th century, television screens and newspaper articles around the world portrayed Tehrān as a deeply religious city steeped in tradition, fighting against modernization and Westernization. While the Iranian self-image is that of an ancient people with a long history and a rich heritage, Tehrān challenges these images, as the corporeal city is relatively young. Most buildings were built after the mid-1960s, and the population’s mean age is about 31 years; many of the city’s institutions are even younger. This often uneasy coexistence of old and new, of continuity and change, and a deep social divide between rich and poor characterize the city, causing vitality as well as tension and upheaval—reflected in two revolutions and many social movements during the 20th century.