The origin of the name Tehran is uncertain. The settlement of Tehran dates back over 7,000 years.
Tehran is situated within the historical region of Media (Old Persian: 𐎶𐎠𐎭 Māda) in northwestern Iran. By the time of the Median Empire, a part of the territory of present-day Tehran was a suburb of the prominent Median city of Rhages (Old Persian: 𐎼𐎥𐎠 Ragā). In the Avesta's Videvdat (i, 15), Rhages is mentioned as the 12th sacred place created by Ohrmazd. In Old Persian inscriptions, Rhages appears as a province (Bistun 2, 10–18). From Rhages, Darius I sent reinforcements to his father Hystaspes, who was putting down the rebellion in Parthia (Bistun 3, 1–10). In some Middle Persian texts, Rhages is given as the birthplace of Zoroaster, although modern historians generally place the birth of Zoroaster in Khorasan. Rhages's modern-day inheritor, Ray, is a city located towards the southern end of Tehran, which has been absorbed into the metropolitan area of Greater Tehran.
Mount Damavand, the highest peak of Iran, which is located near Tehran, is an important location in Ferdowsi's Šāhnāme, the Iranian epic poem that is based on the ancient legends of Iran. It appears in the epics as the homeland of the protoplast Keyumars, the birthplace of king Manuchehr, the place where king Freydun binds the dragon fiend Aždahāk (Bivarasp), and the place where Arash shot his arrow from.
During the reign of the Sassanian Empire, in 641, Yazdgerd III issued his last appeal to the nation from Rhages, before fleeing to Khorasan. Rhages was dominated by the Parthian Mehran family, and Siyavakhsh—the son of Mehran the son of Bahram Chobin—who resisted the 7th-century Muslim invasion of Iran. Because of this resistance, when the Arabs captured Rhages, they ordered the town to be destroyed and rebuilt anew by traitor aristocrat Farrukhzad.
In the 9th century, Tehran was a well known village, but less known than the city of Rhages, which was flourishing nearby. Rhages was described in detail by 10th-century Muslim geographers. Despite the interest that Arabian Baghdad displayed in Rhages, the number of Arabs in the city remained insignificant and the population mainly consisted of Iranians of all classes.
The Oghuz Turks invaded Rhages discretely in 1035 and 1042, but the city was recovered under the reigns of the Seljuks and the Khwarezmians. Medieval writer Najm od Din Razi declared the population of Rhages about 500,000 before the Mongol invasion. In the 13th century, the Mongols invaded Rhages, laid the city in ruins, and massacred many of its inhabitants. Following the invasion, many of the city's inhabitants escaped to Tehran.
In July 1404, Castilian ambassador Ruy González de Clavijo visited Tehran while on a journey to Samarkand, the capital of Turco-Mongol conqueror Timur, who ruled Iran at the time. In his diary, Tehran was described as an unwalled region.
Early modern era
Italian traveler Pietro della Valle passed through Tehran overnight in 1618, and in his memoirs, he mentioned the city as Taheran. English traveler Thomas Herbert entered Tehran in 1627, and mentioned it as Tyroan. Herbert stated that the city had about 3,000 houses.
In the early 18th century, Karim Khan of the Zand dynasty ordered a palace and a government office to be built in Tehran, possibly to declare the city his capital; but he later moved his government to Shiraz. Eventually, Qajar king Agha Mohammad Khan chose Tehran as the capital of Iran in 1776.
Agha Mohammad Khan's choice of his capital was based on a similar concern for the control of both northern and southern Iran. He was aware of the loyalties of the inhabitants of former capitals Isfahan and Shiraz to the Safavid and Zand dynasties respectively, and was wary of the power of the local notables in these cities. Thus, he probably viewed Tehran's lack of a substantial urban structure as a blessing, because it minimized the chances of resistance to his rule by the notables and by the general public. Moreover, he had to remain within close reach of Azerbaijan and Iran's integral northern and southern Caucasian territories—at that time not yet irrevocably lost per the treaties of Golestan and Turkmenchay to the neighboring Russian Empire—which would follow in the course of the 19th century.
After 50 years of Qajar rule, the city still barely had more than 80,000 inhabitants. Up until the 1870s, Tehran consisted of a walled citadel, a roofed bazaar, and the three main neighborhoods of Udlajan, Chale-Meydan, and Sangelaj, where the majority resided.
The first development plan of Tehran in 1855 emphasized the traditional spatial structure. Architecture, however, found an eclectic expression to reflect the new lifestyle. The second major planning exercise in Tehran took place under the supervision of Dar ol Fonun. The 1878 plan of Tehran included new city walls, in the form of a perfect octagon with an area of 19 square kilometers, which mimicked the Renaissance cities of Europe.
Late modern era
The growing social awareness of civil rights resulted in the Constitutional Revolution and the first constitution of Iran in 1906. On June 2, 1907, the parliament passed a law on local governance known as the Baladie (municipal law), providing a detailed outline on issues such as the role of councils within the city, the members' qualifications, the election process, and the requirements to be entitled to vote. The then Qajar monarch Mohammad Ali Shah abolished the constitution and bombarded the parliament with the help of the Russian-controlled Cossack Brigade on June 23, 1908. That followed the capture of the city by the revolutionary forces of Ali-Qoli Khan (Sardar Asad II) and Mohammad Vali Khan (Sepahsalar e Tonekaboni) on July 13, 1909. As a result, the monarch was exiled and replaced with his son Ahmad, and the parliament was re-established.
After World War I, the constituent assembly elected Reza Shah of the Pahlavi dynasty as the new monarch, who immediately suspended the Baladie law of 1907, replacing the decentralized and autonomous city councils with centralist approaches of governance and planning.
From the 1920s to the 1930s, under the rule of Reza Shah, the city was essentially rebuilt from scratch. That followed a systematic demolition of several old buildings, including parts of the Golestan Palace, Tekye Dowlat, and Tupkhane Square, which were replaced with modern buildings influenced by classical Iranian architecture, particularly the building of the National Bank, the Police Headquarters, the Telegraph Office, and the Military Academy.
The changes in urban fabric started with the street-widening act of 1933, which served as a framework for changes in all other cities. The Grand Bazaar was divided in half and many historic buildings were demolished to be replaced with wide straight avenues. As a result, the traditional texture of the city was replaced with intersecting cruciform streets that created large roundabouts, located on major public spaces such as the bazaar.
As an attempt to create a network for easy transportation within the city, the old citadel and city walls were demolished in 1937, replaced by wide streets cutting through the urban fabric. The new city map of Tehran in 1937 was heavily influenced by modernist planning patterns of zoning and gridiron networks.
During World War II, Soviet and British troops entered the city. In 1943, Tehran was the site of the Tehran Conference, attended by U.S. President Franklin D. Roosevelt, Soviet Premier Joseph Stalin, and British Prime Minister Winston Churchill.
A former Parliament Building, built in the 1920s
A street in Tehran during the 1930s
National Bank of Iran, Sabze Meydan, in the 1940s
The establishment of the planning organization of Iran in 1948 resulted in the first socio-economic development plan to cover from 1949 to 1955. These plans not only failed to slow the unbalanced growth of Tehran, but with the 1962 land reforms that Reza Shah's son and successor Mohammad Reza Shah named the White Revolution, Tehran's chaotic growth was further accentuated.
Throughout the 1960s and 1970s, Tehran was rapidly developing under the reign of Mohammad Reza Shah. Modern buildings altered the face of Tehran and ambitious projects were envisioned for the following decades. In order to resolve the problem of social exclusion, the first comprehensive plan of Tehran was approved in 1968. The consortium of Iranian architect Abd-ol-Aziz Farmanfarmaian and the American firm of Victor Gruen Associates identified the main problems blighting the city to be high density suburbs, air and water pollution, inefficient infrastructure, unemployment, and rural-urban migration. Eventually, the whole plan was marginalized by the 1979 Revolution and the subsequent Iran–Iraq War.
Tehran's most famous landmark, the Azadi Tower, was built by the order of the Shah in 1971. It was designed by Hossein Amanat, an architect who won a competition to design the monument, combining elements of classical Sassanian architecture with post-classical Iranian architecture. Formerly known as the Shahyad Tower, it was built in commemoration of the 2,500th year of the foundation of the Imperial State of Iran.
During the 1980–1988 Iran–Iraq War, Tehran was the target of repeated Scud missile attacks and air strikes.
The 435-meter-high Milad Tower, which was part of the proposed development projects in pre-revolutionary Iran, was completed in 2007, and has thence become a famous landmark of Tehran. The 270-meter of Tabiat Bridge is a newly-built landmark, designed by award winning architect Leila Araghian, which was completed in 2014.