Tehran

Overview

Tehran is the capital of Iran and Tehran Province, and the country’s principal center of government, commerce, industry and transport. Greater Tehran held about 15 million people in 2025, roughly 15 percent of Iran’s population. Its size gives decisions made in the capital national reach: state institutions, major employers, universities and transport connections draw people and resources from across the country. Tehran is also the seat of an Iranian regime whose nuclear program, support for armed organizations and confrontation with Israel have made the city a focus of regional diplomacy and security planning.

The city became Iran’s capital in 1796, when Agha Mohammad Khan of the Qajar dynasty chose it partly to keep his government close to Iranian territories in the Caucasus and away from factions associated with earlier ruling dynasties. Large-scale demolition and rebuilding began in the 1920s. Migration during the twentieth century then transformed Tehran from a dynastic capital into a vast metropolis. Tehran Province has continued to receive about 20 percent of Iran’s internal migrants; officials have reported roughly 200,000 people moving to Tehran annually. This growth has increased pressure on housing, roads, water supplies and public services.

Tehran’s public life reflects several layers of Iranian history. It hosted the Allied leaders’ Tehran Conference in 1943, became a center of the Iranian Revolution in 1979, and was the site of the seizure of the American embassy later that year. It remains a place where political authority and public opposition meet. Its universities have been centers of education and protest, while the regime’s security institutions, including the Islamic Revolutionary Guard Corps and Basij, maintain a substantial presence in and around the capital.

Geography

Tehran lies in north-central Iran. Its metropolitan area extends well beyond the central city into surrounding towns and districts, making figures for Tehran’s population dependent on the boundary used. The capital’s concentration of residents, industry and economic activity is unmatched elsewhere in Iran. Employment and access to state institutions have attracted successive waves of migrants, while growth at the metropolitan edge has placed further demands on transport and infrastructure. Several towns around Tehran have higher shares of non-Persian residents and stronger use of minority languages than the city itself.

Tehran is linked to the rest of Iran and to international destinations through Mehrabad and Khomeini international airports, a central railway station and major highways. The Tehran Metro carries passengers across the metropolitan area alongside bus rapid transit and other road services. The scale of travel is immense: Tehran records more than 42 million vehicle-trip segments each day, including about 19 million complete journeys. Heavy traffic contributes to air pollution, an enduring public health and environmental problem in the capital.

Water scarcity has become a defining constraint on the city’s growth. Drought has reduced rainfall, but decades of unregulated extraction, political neglect and short-term engineering decisions have compounded the shortage. In November 2025, dams supplying Tehran held only about 14 percent of their capacity, while Lar Dam, a crucial source, stood at barely 1 percent. Pumping from aquifers to make up the deficit has caused parts of the ground beneath Tehran to sink by up to 25 centimeters per year. Subsidence has damaged roads, pipelines and building foundations; it has also affected rail lines, sections of the Metro and airport runways. Sinkholes have forced evacuations in residential areas.

These pressures have revived debate over whether Iran’s capital can remain in Tehran. President Masoud Pezeshkian warned in October 2025 that moving it had become necessary. Relocation, however, would involve shifting institutions and services built around a metropolitan population of millions. The debate therefore concerns both the city’s environmental limits and the Iranian regime’s capacity to repair water and infrastructure systems after decades of growth.

Ancient and biblical history

Part of present-day Tehran occupies the area of the ancient Median settlement called Rhaga in the Avesta. Rhaga’s presence establishes a history of settlement in the area long before Tehran became a capital. The ancient site and the later city should not be treated as identical urban entities: Tehran’s political importance arose much later. Rhaga was destroyed by the Mongols in the early thirteenth century, and its remains lie toward the southern end of the modern city.

No specific biblical event in the supplied historical record is located in Tehran. Its ancient significance rests instead on the settlement at Rhaga and the wider history of Iran. Tehran’s rise to national prominence belongs chiefly to the Qajar period, when its location served Agha Mohammad Khan’s political and strategic aims. That choice connected an existing settlement to a new national role that subsequent rulers retained.

Jewish history

Iranian Jews have been part of Tehran’s urban society. During the 1940s, Iranian Jews developed youth groups, schools, a hospital, women’s organizations and newspapers in several Iranian cities. By around 2000, Iran’s Jewish community numbered about 25,000 and was centered in Tehran, Shiraz and Isfahan. A small Jewish community remains in Tehran after most of the city’s Jews left for the United States or Israel.

The community’s continued presence forms part of Tehran’s religious and ethnic diversity, even as emigration has reduced its size. Jewish institutions in the capital developed within a broader Iranian Jewish history rather than as a separate history of the city alone. Tehran’s role as a center of education, employment and government helped make it one of the principal homes of Iranian Jews in the twentieth century.

Most Tehran residents speak Persian, and Persians form the city’s largest ethnic community. Tehran also includes people from other Iranian communities, among them Kurds, as well as residents whose families moved from other parts of the country. Migration has brought these communities into the capital while leaving stronger concentrations of some minority languages in surrounding towns. The city’s remaining Jewish population is one part of this wider social landscape.

Modern history

Agha Mohammad Khan’s selection of Tehran in 1796 gave the city a role that survived the Qajar dynasty. He wanted a capital within reach of Iran’s Caucasian territories and removed from rival factions tied to previous rulers. Iran later lost its territories in the Caucasus through the Russo-Persian Wars, but Tehran remained the seat of government. Beginning in the 1920s, demolition and rebuilding altered much of its urban fabric. Continued migration through the twentieth century enlarged the city and tied its development to economic and political changes across Iran.

Tehran hosted a major Allied meeting during the Second World War. From November 28 to December 1, 1943, United States President Franklin D. Roosevelt, British Prime Minister Winston Churchill and Soviet leader Joseph Stalin met in the city. The Tehran Conference addressed the war and questions about Europe’s postwar settlement. Its location briefly made the Iranian capital a center of decisions extending far beyond the Middle East.

The city was central to the upheaval of 1979. After the Iranian Revolution, Ruhollah Khomeini spent only a few months in Qom before a heart attack prompted his move to Tehran. On November 4, 1979, revolutionary students climbed over the wall of the United States embassy and seized American diplomats and staff. The ensuing Iran hostage crisis lasted 444 days. The seizure became a defining event in the new regime’s confrontation with the United States and left a lasting mark on relations between the two countries.

Tehran has also been a setting for political dissent and state repression. During unrest in the capital, the Guard Corps brought Basij members from outside Tehran to suppress protesters. On May 13, 2019, Basij members and pro-regime vigilantes forcibly dispersed University of Tehran students protesting mandatory hijab rules. On November 22, 2020, security agents raided Baháʼí homes in Tehran and several other cities. Those raids formed part of the wider persecution of Baháʼís under the Iranian regime.

As Iran’s capital, Tehran hosts meetings through which the regime conducts regional diplomacy. After Russia’s February 2022 invasion of Ukraine, Ebrahim Raisi, Vladimir Putin and Recep Tayyip Erdoğan met there for an Astana Process summit concerning Syria. Leaders of the Kurdistan Regional Government have also visited Tehran for talks about security and disputes involving Baghdad and Erbil. Such meetings demonstrate the city’s diplomatic function, though the interests of the states and governments represented do not always coincide.

Security

Tehran is the command center of the Iranian regime’s regional security network. The Islamic Revolutionary Guard Corps and its Quds Force use relationships with armed organizations across the Middle East to extend the regime’s reach. The Guard Corps’ provincial structure includes separate units for Greater Tehran and Tehran City, while its Muhammad Rasoul Allah Corps has included a Basij contingent assigned to secure the capital. These arrangements reflect the city’s importance to the regime’s continuity and to its ability to direct operations abroad.

The regime’s support for Hamas, a terrorist organization committed to attacking Israel, developed into a sustained relationship. Later in 1991, the regime invited Hamas to a conference in Tehran with other groups it backed. Hamas Politburo chief Musa Abu Marzouk led a delegation there for meetings with senior Iranian officials in 1992. Founder Ahmed Yassin visited in 1998 and praised Iranian support for the organization’s campaign against Israel. During Ismail Haniyeh’s December 2006 visit, the regime pledged $250 million to the Hamas-led government. Tehran thus served as a meeting place and political base for a relationship that also involved money, weapons and training.

Tehran has hosted leaders of other organizations in the regime’s network. On May 23, 2024, Guard Corps commander Hossein Salami and Quds Force commander Esmail Qaani met regional leaders in the capital during events surrounding Ebrahim Raisi’s funeral. Pezeshkian met senior figures from the regime’s Axis of Resistance for his July 2024 inauguration and pledged continued support. On July 29, he met Islamic Jihad leader Ziyad al-Nakhalah and reaffirmed support for that terrorist organization. Tehran’s role in these meetings made the city an organizing center for the regime’s confrontation with Israel.

Hamas political leader Ismail Haniyeh traveled to Tehran for Pezeshkian’s inauguration and met the president on July 30, 2024. He was killed in the city during the night of July 30–31. The assassination of Ismail Haniyeh exposed a failure of security around a visiting Hamas leader whom the regime had welcomed. It also underscored how Tehran itself had become a setting for the conflict between Iran’s regime, its armed partners and Israel.

The regime’s nuclear program is central to that confrontation. By February 2025, it held approximately 275 kilograms of uranium enriched to 60 percent purity. Iran’s continued enrichment, missile capabilities and support for armed groups have made the possibility of nuclear weapons a grave concern for Israel. The regime launched two large missile-and-drone barrages against Israel; both failed to achieve their intended effect. During the 2025 war, Mossad operations inside Iran contributed to Israel’s June 14 announcement that it had established air superiority from western Iran to Tehran. The capital’s role as the seat of the regime made it both a decision-making center and a focus of military pressure.

Present day

Tehran remains Iran’s dominant metropolitan and political center. Government bodies, universities, industry and commercial activity are concentrated there, while continuing migration adds residents faster than infrastructure can readily absorb them. Persian is the majority language, but the city’s population reflects movement from many parts of Iran. Its airports, railway station, Metro and highways sustain daily life on a vast scale, even as congestion and air pollution impose costs on residents.

The capital also concentrates the consequences of the Iranian regime’s choices. Money directed to military programs and armed groups abroad sits alongside severe economic hardship at home. Tehran’s water crisis illustrates a different long-term cost: reduced rainfall has intensified shortages, while over-pumping and poorly governed development have damaged the ground and infrastructure beneath the city. Pezeshkian’s 2025 call to move the capital brought those pressures into national debate. Whether or not Iran relocates its government, the city’s population and economic weight make repairing Tehran’s water, transport and environmental systems an enduring national task.