A definitely must visit if you are in Istanbul. Th...

A definitely must visit if you are in Istanbul. There are some personal guides offering their service on the entrance if you like. But inside you can also rent audio guide, or (like me) you can just walk around and read the explanation box in every areas. There is also a video about the history of this museum that you can watch inside for free.

I think this is the best historical place in the city. Once the biggest church, then became a mosque, and now a museum. And you will be fascinated to know that this building is very old but once was very beautiful.