Travelling from across the country, huge numbers of mourners have converged on the mausoleum of Imam Khomeini in southern Tehran to pay their tributes.
Hundreds of foreign guests, including scholars and researchers, are also attending the ceremonies.
Similar mourning processions are being held elsewhere across Iran, with the participants renewing their allegiance to the ideals of the Islamic Revolution, led by the late Imam Khomeini and his successor Ayatollah Khamenei.
Grand Ayatollah Seyyed Rouhollah Mousavi Khomeini, better known as Imam Khomeini, was born to a family of religious scholars in 1902 in the central Iranian city of Khomein.
Imam Khomeini contributed many years of his life to resistance against the US-backed Pahlavi dynasty, and eventually paved the way for its downfall in the 1979 Islamic Revolution.
In the pre-Revolution era, Imam Khomeini spent more than 15 years in exile for his stiff opposition to the last monarch, Mohammad Reza Pahlavi, mostly for his association with Western imperialists.
While in exile, the politico-religious leader, who enjoyed immense public support in the country, continued to guide the uprising against the Pahlavi regime.
He was not allowed to return to homeland during Pahlavi’s reign, and only came back home on February 1, 1979 after the monarch finally gave into angry popular demonstrations and fled the country, never to return.
The Pahlavi dynasty fully collapsed 10 days later on February 11. Iranians then voted in a national referendum in April that year for the country to become Islamic Republic, an establishment architected by Imam Khomeini.
Imam Khomeini passed away on June 3, 1989 at the age of 87.
