Supreme Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei will address the large spiritual and religious gathering at the holy site later.
This comes as huge numbers of mourners have converged on the holy shrine in southern Tehran to commemorate the 27th anniversary of the passing away of Imam Khomeini and pay their tributes. Some 1.3 million people are estimated to gather at the complex.
Millions of Iranians and devotees are taking part in series of separate ceremonies across Iran and other parts of the world to marks the ceremony.
Participants each year renew their allegiance to the ideals of the Islamic Revolution and his founder