RALEIGH, NC - The annual Wide Open Bluegrass Festival is in full swing across downtown Raleigh. 

Over 100 performers, from across the world, will play music on seven different stages along Fayetteville street. 

But before the headliners took the stage,  hundreds of bluegrass musicians took over the Convention Center Friday morning for to jam in what they call "jam circles," where strangers play mucis with strangers.

Some say the jam sessions are the best of the entire festival. 

"It's not rehearsed, it's spontaneous, it's not like a band up on stage where they work out all their arrangement and all their vocal harmonies, its just participating," said Ron Perry, a festival attendee.

The festival, a free event, is considered the largest free urban bluegrass festival in the world.