Museum Mayer van den Bergh is one mans collection, I especially loved Pieter Bruegel the Elder's paintings, fascinating pictures with so much going on you can stand there for ages seeing new things in each one.
Ruben's House. I remember feeling very comfortable around the many many paintings of Peter Paul Ruben's well developed women :-)
Museum of Plantin-Moretus and Print Room. Some wonderful old classics in this Museum.
Museum Brouwershuis (Brewers House) I don't remember this one, beer was David's thing. This Museum is closed at the moment.
I notice in David's writing that the Museum's we visited were free, I guess they had to be free for us to afford to visit them but now I see you can pay 3 Euros for entry.