Sigur Rós
O2, Dublin
****

On paper, Sigur Rós shouldn’t be one of the biggest bands in the world. Their music is largely instrumental; they sing in words and languages that are incomprehensible to most (or indeed entirely made up); and there is an artful coolness to their aesthetic that might leave some people cold. But all of that ignores the music, which the band unleash into the O2 as a headline act for the first time.

Sigur Rós carved out their core sound on their early albums and haven’t strayed much from that template in the intervening years. These are tracks built on a majestic scale, immense constituent musical parts that shift around each other like ships in a harbour – and in the cavernous space of this venue, they find a berth to match their ambition.

Chords the size of cathedrals unsheathe at a pace somewhere around half a heartbeat; guitar riffs, bowed and beaten, strafe overhead; drum beats and bass rumble in like minor tectonic events; there are bursts of bright brass and strings; and above it all is Jón Birgisson’s ringing, unearthly vocal, soaring into the ether.

Each song is matched with an intricate visual display on a giant letterbox screen above the stage. The scrolling flow plays a neat visual trick, making the band appear as if the stage is rising incrementally. Dark lines and rough shapes reveal themselves as Iceland’s volcanic mountainscape. Lighthouses emerge from the gloom. Shipyards shuffle into gigantic life while ferries are built and seemingly destroyed. A galaxy unfolds. And sparks spin out and cascade down the screen in sudden, amber bursts, matched by onstage lightbulbs that burn brightly in the dark, and videos and spotlights that favour no one in particular.

As a whole, this doesn’t seem like a concert so much as an immense, intricate and overwhelming installation piece.

Like many works of art, it’s undoubtedly beautiful but it also initially feels a little distant. As the gig winds its way to an epic conclusion, though, the ensemble shift through their gears, whip up the volume and lend things a grit and edge that take it into more muscular musical territory.

Early favourites such as E-bow and Hoppípolla are blown out of the water by the final salvo. When Festival doubles its march, it seems like a fitting end to a fine show, but the returning encore is peerless.

Svefn-g-englar still sounds improbably serene and here the crowd seem awestruck. That turns to a giddy euphoria with Rafstraumur, probably the nearest thing Sigur Rós will produce to a pop song. Then it's a breathless, tooled-up Popplagið that ends the concert in chaotic, blistering fashion with as much power and intent as an army on the move.