Parisians, like most hip urbanites, wear black. Until something darker comes along.
I wouldn't call these steps a stoop, although the photo reminded me of hanging out on one. These columns are part of the southeastern façade of the Dôme des Invalides, the centerpiece of the massive Hôtel des Invalides complex built by Louis XIV in the seventeenth century, and the final resting place of Napoleon Bonaparte. It's one of the more recognizable monuments in Paris, although maybe not from this picture.