This is the must see place in Malta in my point of view. The inner decorations are definitely worth a visit. You can check the heraldry of the knights of the Malta. Each chaple has its own stories and the audio guide will give you a detailed description about the stories. The most important thing for this place is the paintings from Caravaggio. It is awe-inspiring to see the masterpieces of Caravaggio here. The audio guide gives you a detailed explanation of the background of the paintings as well as a brief introduction of the life of this controversial painter from the renaissance. Even though I visited this place off the peak season, there were still so many tourists and I was lining up in front of the entrance for half an hour. After you go in, before you may check out Caravaggio's paintings, you have to line up again and wait. If you really want to get the most out of this visit, it can easily take couple hours just in this cathedral. It is not allowed to eat inside this cathedral but right in front of the entrance there are trash cans. In general the experience was very nice and this is definitely the top 1 place of Malta.