I chose a 9hr layover because I realized that Turkish Airlines provides all their guests to go on custom, organized tours according to how long your layover is.
We took a 3hr bus tour throughout the city to see all its beauty and cathedrals and then left the bus to go out on our own.
It was cold and beautiful, we walked and shopped around but after some vigorous sightseeing, it was time for some real shopping! !
OMG they have everything; food, restaurants, tea shops, shopping of all kind, jewlery and soooo many shops that sell teas and Turkish Delights.