Cox is a bar on rue des Archives, the street that carries most of the gay nightlife in the Marais. The room is small, so the crowd spills out onto the pavement, and that pavement is really where the bar happens.
Music comes from rotating DJs. The crowd is mixed in age and gets dense enough that standing outside with a drink is the normal way to be there.
The bar has been on this corner since the mid 1990s and is one of the most visible addresses in the quarter. It sits directly across from Open Cafe, which makes this junction the busiest corner of gay Paris.