Each year, Iran marks al-Quds - or Jerusalem - Day, bringing millions of people on to the streets for rallies, celebrations and speeches. Its overarching theme is support for the Palestinians and fierce denunciation of Israel, and is as much an expression of policy as ritual.
Here are some lesser known points about the occasion, and what it reveals about Iran:
Jerusalem Day was not the brainchild of Ayatollah Khomeini, the founder of Iran's Revolution in 1979. However he took credit for it. The idea came from Ebrahim Yazdi, Iran's second foreign minister after the revolution: a liberal by the standards of the Iran's ruling clerics back in 1979 and now.
Mr Yazdi took the idea to Ayatollah Khomeini who subsequently proposed it publicly in August 1979 amid deepening tensions between Israel and Lebanon. Mr Yazdi's name was not mentioned in the speech.
Mr Yazdi resigned after the storming of the US embassy in Tehran; his party, Iran's Freedom Movement, was disbanded. He had more reasons to be disgruntled than someone else taking credit for his idea. Mr Yazdi never protested, perhaps out of a reluctance not to be associated with Iran's subsequent foreign policy on the Israeli issue.
All about Jerusalem?
Jerusalem Day in Iran is nominally about Jerusalem. Yet in content it is anything but. The slogans chanted during the rallies organised on Jerusalem Day are primarily "Death to Israel", a refrain that sounds as familiar to Iranian ears as any political slogan can get. The speeches and sermons are a repeat of the same narrative over and over: Israel is a usurper regime - not a country - and as a state, it lacks legitimacy.
However, the repetition of this narrative, and the rhetoric that goes with it, has had the effect of turning the plight of the Palestinians, the victims in this narrative, into a given. Jerusalem Day has turned into an occasion that says more about the political mood in Iran than the Palestinians' own situation.
Jerusalem Day rallies are a must for Iranian politicians. Any politician who hopes to establish their credentials has to be seen and hope to be heard delivering a tirade against Israel. It confirms their loyalties and reiterates their identification with what has become an unshakable tenet of Iran's foreign policy.
The official stance is that Israel is, as a matter of moral principle, illegitimate. However, it does not follow from this that Iran is under the obligation to take direct and pre-emptive action to destroy Israel. This will happen in due course, the rhetoric goes.
Iranians are well-practised in how to express this idea in short soundbites that are broadcast non-stop during the day of the rallies on state radio and TV. Iranian politicians have particularly become skilled at this. The sentences express a moral outrage over Israel's existence as well as its actions but fall short of requiring that Iran does anything too harsh about this "moral violation".
President Ahmadinejad, however, tried introducing a new element to the traditional narrative: Holocaust denial. His attempts failed and the Supreme Leader, who shares Mr Ahmadinejad's denial but keeps it low-profile, along with Mr Ahmadinejad's political rivals, did not allow for this deviation.
What happens in Iran, stays in Iran
The idea behind Jerusalem Day rallies was to gather all fasting Muslims every year on the last Friday of Ramadan to show their opposition to the existence of Israel. However, Jerusalem Day did not develop beyond an Iranian experience.
Iranian leaders may have initially been motivated by the desire to further an anti-Israeli drive. However, the need to consolidate and project Iran's leadership and influence in the Islamic world as well as intimidating opposition forces inside remained as an incentive to keep the tradition alive.
Jerusalem Day did not achieve the former. As it turned out, whatever leadership and influence Iran wields in the Islamic world has little to do with the rallies on Jerusalem Day. Apart from these annual rallies in some Western and Asian capitals, usually organised and financed by Iran, the ritual never took root among Muslims at large.
The art of crowd gathering
Jerusalem Day is one of two important country-wide, annual occasions that, like birthdays and anniversaries, mark Iran's political calendar. The other occasion is, of course, the anniversary of Iran's Islamic revolution of 11 February 1979. Jerusalem Day provides a yearly photo opportunity for the authorities to showcase the apparent scale of their support base.
The rallies have changed little from the early years: the same types of participants, the same slogans and speeches and speakers, the same routes for demonstrators, and the same level of energy, and by extension the same relevance of Jerusalem Day to solving the Israeli-Palestinian issue.
Jerusalem Day rallies are a massive logistical undertaking and an operational challenge with all official institutions at all levels, and all regions in Iran, competing to bring out as many of their personnel onto the streets as they can. Each year, old banners and posters are pulled out of the closet, as well as new ones getting printed.
Iranian dissidents tried to take advantage of the 2009 Jerusalem Day rallies in the aftermath of the contested presidential elections to steal the limelight and chant the politically heretical slogan "Neither Gaza nor Lebanon, God Save Iran". This attempt enjoyed qualified success but the opposition failed to replicate this as a political strategy of civil resistance.