Ragusa - the largest market is held each Wednesday at the football stadium MAP. Smaller markets are held on other week days at different locations around the city. Its best to check with the locals in each neighborhood to determine times and places.
Marina di Ragusa- Tuesdays
Modicia - Thursdays, 08:00 to 13:00 but the location alternates between to sites. MAP1 - MAP2 Many different foods and spices, clothing and household items are sold at both locations. There is also a very large antique market on the last Sunday of each month MAP
Marina di Modica - There is a Saturday food market in the mornings and a Sunday clothing market that runs into the late afternoon.