The marché Saxe-Breteuil located in the 7th arrondissement, actually it right not the border of the 15th arrondissement. We took the metro line 10 to the Ségur metro stop, take exit #1 and at the top of the stairs turn right and walk up Rue Pérignon. As you walk up the street the 7th is on you left and the 15th on your right.
The market is large, covering the median on Avenue de Saxe with two aisles of stalls, we didn’t count the stalls but its long with a lot of activity. It’s a good market for those who may be concerned about traveling to an area in Paris they are not familiar with to see a large combination market with food and clothing etc.