The fire festival is an ancient ritual going back to Zoroastrian times. Traditionally, people jump through bonfires chanting a formula that is meant to bring good health.
Iranians are celebrating the arrival of their biggest annual festival, Norouz or New Year, which marks the beginning of the Iranian solar year.
The event is accompanied by many special customs and rituals, which date back to well before the advent of Islam in the 7th century AD.
For a short while after the Islamic revolution in 1979, the authorities in Teheran attempted to discourage Norouz celebrations and other pre-Islamic customs.
But they were just too deeply rooted in the Iranian culture and psyche to be eliminated by decree.
One of the most important nights in the calendar is chharshanbeh suri - the fire festival - held on the last Tuesday night of the Iranian old year.
It may sound like a cross between a battleground and a disco, but it is one of many customs going back before Islamic times, which are now being re-embraced with great fervour by the Iranian people.
The fire festival is an ancient ritual going back to
Zoroastrian times. Traditionally, people jump through bonfires chanting a formula that is meant to
bring good health.
This year, there were bonfires all over town, but fireworks and dangerous home-made explosives too, as young people in their thousands took over the smoke-filled streets.
Islamic identity
For some the wild scenes are almost a political statement of resistance to the Islamic identity the government is trying to impose.
"It's blatant defiance of all the hard-core Islamists are standing for. All these kids have all kinds of frustrations, and this is one of the occasions they can vent their frustrations, " said one observer.
But Norouz itself, although its roots go back well before the advent of Islam in the 7th
century, is not a controversial occasion.
It is the big Iranian feast, and that means shopping is the order of the day - in fact for many days beforehand, as people prepare to mark what for all Iranians is a very special time.
Traditions preserved
"First of all, it's an Iranian new year, so it's very important for us as Iranians. Secondly, it's spring, it's the festival of nature. So it should be celebrated all around the world, not just here, " one middle-aged woman told me.
As he sipped a cup of tea, an old man explained the significance of the event for Iranians.
"It's very important for us," he said. "It's an ancient celebration and it's one of our traditions. If we don't celebrate it, it won't be passed on to the next generation and it will die out."
Maryam Sinaie, an expert on early Iranian culture, believes these pre-Islamic customs -
some of which have been absorbed or adopted by Islam - are so strong they will always survive.
"I think they are very very deeply rooted, because after Iranians turned Muslim, they continued celebrating Norouz, just as an Islamic feast, " she said.
"It's embedded in their lives, so deeply and seriously that I don't think in any way they can forget them. They will continue to celebrate the event."
Nostalgia
But Daryush Shayegan, one of Iran's top thinkers and writers, believes there is a contradiction, and that people are turning increasingly to the pre-Islamic past out of disaffection.
"For 20 years, life has been very difficult in Iran," he said. "The more it gets difficult, the more people become nostalgic about the past. And then many people make a difference between their Islam and the official Islam.
"We are Muslims, we're pious, we make our prayers, but then this form of instrumentalised Islam is not our Islam. It's become an instrument of power and repression. And with this attitude of mind, there's a shift towards old Iran."
Can Iran's pre-Islamic past, its Islamic identity, and now, the unavoidable impact of modern
globalisation be reconciled, or will the country always be at odds with itself?
An identity problem, but one far from the minds of ordinary Iranians at Norouz, as they go about the serious business of having a good time.