Recommendations for Istanbul

[IstanbulBaby]

Hi,
We are off to Istanbul the last week in June for a week. Any recommendations/definite things to do/to avoid?
What's the style like?

All advice welcome

We saw a really good Whirling Dervish show at Hodjapasha Culture Centre.
If you’ve got time, take a ferry to Princes’ islands. I’d normally suggest exploring by bike, but in this weather it might be preferable to chill on a beach. There are loads of lovely small cafes too.
Another nice place to escape the heat is Gülhane park, and you get quite a nice breeze on a Bosphorus boat cruise too.
If you’re arty or feeling creative, I’d definitely recommend an Ebru marbling class.