For a real history/art history buff, what are the best historic sites or museums in Istanbul? I'm thinking of places either NOT covered, or glossed over, in Rick's Istanbul book or Frommer's. I'm thinking ancient, Byzantine, or Ottoman era.
My main trip will be 4 days with family (people with a much lower museum tolerance); I may stay on by myself to cover some things in greater depth. Plus, if there are nuts like me out there (I'm the sort that would spend 4 days in the Vatican collection and feel like I missed too much), how much add-on time should I allow for the Topkapi Palace Museum collections?