Unexpected added-value is found in Montresor and who knew? On rue Marche in the former Carders Hall (1750 wool market), one may visit the free 'Gemmail' exhibit. The art is a cousin stained-glass and is illuminated from behind. Both Cézanne and also Picasso once experimented in this rare and colorful art form. *Merci to JP Sala-Malherbe for donating this welcome bit of color underneath timber frames and mansard roof.