I went there two times during my stay. Once after dinner (around 1.00 am) for drinks at the "volume bar" and drinks+appetizers before dinner (around 6-7pm) to a bar across volume (I forgot the name). The latter had free tapas with your drinks at that time and they were delicious. I heard that there is an open-air market at the piazza on Sundays but I didn't have time to go. I bet it was good, seeing the pictures. You can choose to go there any time of the day either just for drinks or lunch/dinner.