Streetfilms’ Elizabeth Press kicks off a series of videos about livable streets in Paris with this look at the city’s two weekly romps on skates — roller-versions of Critical Mass that attract up to 15,000 participants. Notice that the police are an essential part of the proceedings (and they seem to have fun doing it — check out the cops on blades at the 1:35 mark).

Says Elizabeth:

Every Friday night and Sunday afternoon Parisians can take the streets and see their city on skates. And they do, by the thousands! Both mass rides, which are sponsored by different associations, started small and now are institutions of public street life in Paris.

In this video you hear from both Tanao Terra, VP of Pari Roller, organizers of the Friday night skate and Philippe Moulié, President of Rollers & Coquillages, sponsors of the Sunday afternoon Skate.

A little history: The Friday night skates were started by a small group of friends. After the transit strikes in 1995, which forced Parisians to find a new way to get around town, thousands of people began to show up on Friday evenings just to practice moving through the city on roller blades. The numbers inspired Pari Roller to form an official association working with Paris’, and the world’s, first roller blade national police unit.