There is a range of food available from many sources across the city (restaurants, cafes, bufe, tearooms, merked). There are also districts where shops selling similar products will gather.
Yesterday I encountered the hardware section (but not ALL hardware). In a backstreet on the northern edge of the Golden Horn (on the Galata Tower side) there was a collection of the most functional and useful goodies to explore: hand tools, powertools, chainsaws, pumps, impellers, compressors, drills, augurs, taps, toilet seats, paint mixers, washers, drill bits of all sizes and shapes and a thousand other devices and appliances relating to small hardware. It was fascinating to see the gears and cogs of this part of a working city.
A bit further up the hill is the music and musical instrument “area” and over the other side (in the direction of the Bosphorus) is the “antique shop” section.
There’s a day of strolling in this one small part of the city and some excellent things to look at (and maybe buy!)