The Icelandic band's concert Thursday night in Champions Square was a good time, but it wasn't a party.

People who went to Sigur Rós' show at Champions Square last night expecting fun probably went home a little unsatisfied. Perhaps it all depends on your definition of "fun." A generalized fun show usually involves dancing, singing along and having an all-together rowdy time. Thursday's technical, bombastic, impressive performance from the Icelandic post-rockers wasn't a show for that kind of fun.

I've always thought of Sigur Rós' style as a kind of modern classical music, and their live show reinforces that idea. At an orchestra concert, no one is talking, walking around, dancing or doing anything distracting. Many people in the crowd Thursday night looked like they would have rather been in a cramped old theatre, and I don't blame them. Sigur Rós is known for both its loud and soft moments, bandit the indiscernible, sublime vocals from lead singer and guitarist Jón Þór Birgisson - or Jónsi, as he's better known - make every moment a prayer. His voice resonates at any pitch, and he showed off just a little with a high fermata a la Jeff Buckley at the end of "Hallelujah." Some of the most moving moments were delivered by that angelic voice at the show's slowest tempos. Anyone who danced too much during those moments was quickly given a dirty look from someone nearby who had just been jerked out of a trance by the subtlest gyrating. The crowd resisted any kind of physical response throughout the show, even during the stellar build up to the closer, "Popplagið."

But this is expected social etiquette at a Sigur Rós show. Sigur Rós' live show is something to behold, but not something to truly engage in. Maybe on a mental or, as some claim, spiritual level, but many attendees who missed the apparent memo about playing it cool were met with glares as they screamed and emoted about. "Hello, New Orleans" was about as far Jónsi got before picking up his guitar bow for another 10-minute-plus song. He moved around broodingly as he played, but that was the only movement on stage. There was no chance for the guy who tried to start a clap-along, despite his valiant effort.

Sigur Rós has always been built around cranking up the aesthetic. A song starting slow and building up to a big finish would be redundant if it wasn't so damned beautiful, surrounded by flashing lights and a crystal-clear screen playing clips of cells parting and swaying grass. But I found it nice to close my eyes every once and awhile, removing all of the lights and the people walking in and out of the crowd who giggled and chatted as they passed. Were some people being uptight? Surely. But most of the crowd shared that collective vibe. Whether they were prudish or the more active attendees were out of step, there's no denying the talent and prowess that conjured up unforgettable moments like "Hoppípolla" and "Sæglópur." Whether you prefer to sit or stand, Sigur Rós still has the power to move you. Just don't expect a party.