A young couple arrived early and waited inside the drought dry Vaillancourt Fountain in Justin Herman Plaza at the foot of Market Street in San Francisco.

Two young people walked with arms around pillows instead of around each other.

Folks gathered on steps and sipped sodas or coffee or texted on phones, or just stood there holding a grey pillow.

A few arrived in costume. Here a gladiator arrived complete with head-piece, shield, sword and pillow.

Others who gathered posed for each other to immortalize the event in the electronic cloud.

One fellow arrived dressed in a superhero costume. His face was obscured by a mask, but just after this shot he gave a peace sign and thereby indicated he wasn't a robot.

A small crowd of those many waiting gathered alongside the steps to give a rousing cheer.

In advance of the fight, folks posed for fun photos and and laughed at the results of shots taken.

A Dad, with a dad-sized pillow, instructed his son in the finer points of a public pillow fight.