Tehran became the capital of Iran in the 19th century during the Qajar era. Located along and framed by the south side of the Alborz mountain range, home to nearly 8 million people, Tehran is Iran’s most populous city. It has two international airports, Mehrabad and Imam Khomeini, where you will likely land, so this is where you can start your trip to Iran. Tehran is one of the cities with the highest number of urban parks in the world. The capital of Iran is super interesting, cultural and artistic and you will have no problem finding things to do.