This cool, rambling colonial edifice was built as a Dominican convent in the 1740s. (Before that, it was the site of the Hospital de Santa Martha, founded by Vasco de Quiroga and one of Mexico’s first.) Today it houses small artesanías (handicraft shops) on two levels, each specializing in a particular regional craft. Renovations over the years mean there are now five patios rather than the previous 11 (as in the market's name – once is Spanish for 'eleven').
Look for copperware from Santa Clara del Cobre and musical instruments from Paracho, as well as lacquerware, hand-painted ceramics and vibrant textiles. Be sure to check out the Baño Barroco, a tiny 16th-century bathing room.