The anniversary of the Iranian Revolution is celebrated on 22 Bahman, which is the 11th month in the Iranian calendar, equivalent to 11 February in the Gregorian calendar. It commemorates the protests that led to the downfall of the Pahlavi dynasty and the installation of the Islamic Revolutionary which is headed by Imam Khomeini. This political celebration is held on the last day of the celebration called the Ten Days of fajr. The Fajr decade is a ten-day celebration of Ruhollah Khomeini's return to Iran in 1979. The annual celebration is held between 1 and 11 February.Its beginning coincides with the date of Khomeini's arrival and ending with the Iranian Revolution.