Outside Porte de Clignancourt metro station (line 4) at street level, outside McDonald's. Guides wear distinctive pink vests. Address is 79 boulevard Ornano. Spring 2022 advisory. If you plan to ride metro line #4 for a Sunday tour, check the metro schedule in advance, or ride a taxi.
You can cancel up to 24 hours in advance of the experience for a full refund.
Loved the market itself: can be very expensive but is fun to window shop, pick up one small thing, and get away from the purely touristy area.
St Ouen is just outside of the actual city center, and it's an awesome place to shop.