This is the best attraction in the Duomo complex. The only one worth the price of admission. There is a lot to see here, but mostly religious artifacts and art. If you are not a fan, this is not for you. This is not a place for small children as it is very dark and some of the exhibits can be scary to them. This has a one way flow system, so there is no bad time to go, and any time would be the same. This is in the Royal Palace across the street from the Duomo. If you are at the front of the Duomo, this Museum is to the right on the side of the Duomo.