The officials should really do something about this. There are no hours posted on none of the attractions listed in the local maps and books. You are really taking your chances. There are even closed when mosques are not in service or people praying. One good story I read..they stole the stone from the El Djem Amphitheater, the old Roman amphitheater to build this or part of this mosque. It looks nice from the curb but this is all I can comm net on. Plan your visit in the Tunisian cities carefully, you will encounter a bunch of places closed at any hour of the day.