U2 buck the trend of institutions these days in that they deliver what is expected of them. On Friday evening, Larry Mullen Jnr walked on stage at 8.55pm, closely followed by his fellow band members. Larry banged on his drum. The Edge touched on a heavy note. Adam Clayton nodded his bass into action. And then Bono appeared, leaping into the air with scant regard for co-ordination.

For the following two hours a buzz trembled through the 80,000 patrons in Croke Park.

At various junctures, elements of the crowd lapsed into a form of ecstasy not seen this side of a charismatic prayer meeting. The boys were back in town, bringing the unique vibe that has welded their 30 years together.

Say what you like about them. Point out Bono's hypocrisy on tax. Turn your nose at the control freakery which manifests itself every now and then. Lament the dearth of experimentation that was a feature of their earlier incarnation. But give credit where it's due. U2 are unique: in their longevity; in patenting the miracle drug they sprinkle like confetti in live shows; in keeping Bono's feet only a few inches above the ground. They're not bad at the 'oul music either.

On this tour, they are accompanied by the Claw, a hulking structure that towers over the stage and into the sky. In daylight hours, the contraption looks like something that was unceremoniously dropped onto the Croke Park pitch in error from on high. That is how it appears as the band kick off with 'Breathe', from the current No Line On The Horizon album.

Once night falls, the Claw comes into its own, lighting up the stage and sky, displacing any reservations about its role. By the time U2 close with 'Moment of Surrender' – also from the current album – the Claw has been alive and flashing for well over an hour, and could lay claim to occasionally dwarfing Bono's presence. No small job, that.

Opening and closing with new songs from what is by U2 standards a fair to middling album demonstrates the unique confidence and ambition of a rock 'n' roll band in middle age. Nobody else would have the balls to do that.

In between, they flicked through their extensive back pages, turning out rock anthems from 1983's 'Sunday Bloody Sunday', right up to 'City Of Blinding Lights' from 2004. A highlight was an acoustic rendition of 'Stuck in a Moment'.

Bono was on his best behaviour. He made a perfect pitch at raising spirits out of the national doldrums.

"We are smart, we are sexy, in our own way. Undefeatable. Undefeatable," he said. There was a few bars of 'The Aul Triangle' for their departed buddy Ronnie Drew. And there was a touching demonstration of solidarity with Aung San Suu Kyi, when a procession of men and women panned out across the stage wearing face masks of the detained Burmese leader during 'Walk On', a song written for her.

Afterwards, as the crowd spilled out of the stadium, the air was light with the joy which Bono says informs the music. Thirty years-a-growing and there is no sign of any slippage of standards. Long may they run.