Hundreds of people gathered in a Melbourne laneway last night for a secret event set up by US band Bon Iver.

Yesterday the band shared 12 pictures to Instagram which included an address, date, and time, mysteriously leaving out any details about what the information meant.

The cities including Eau Claire in Berlin, Copenhagen, London, Amsterdam, Paris, Brooklyn, Minneapolis, and Melbourne.

Those who travelled to Fitzroy for the surprise event found a stereo balanced on a stack of A3 newspaper-like print outs.

The simple instruction offered was “when the music stops, flip the tape”.

On the tape, fans found the band’s new album 22, A Million , which was released publicly today.

The album was played in 12 different cities across the globe. (Instagram: @melias37)

There were some complaints the volume on the boom box was too low for people at the back of the crowd to hear the album, and the crowd also had to battle rainfall throughout the night.

But most people at the event seemed to enjoy the mystery, taking to social media to describe the odd event.

People spilled out onto the street, the crowd so large that many struggled to hear the music. (Instagram: @gabsryan)

“So stoked I got to share this weirdly intimate evening with a bunch of strangers,” one attendee wrote.

“Was a pretty unique experience to crowd around a cassette player with hundreds of other Melbournians with a sense of adventure and good taste in music,” another said, thanking the band for “bringing people together through art”.