It's not a "stroll through the old city," but a battle replay—telling the story of May 29, 1453 as a single route.
Small group slow travel, includes short-distance transportation by tram, no backtracking, guide for 3 hours, half a day to walk through how a city died and how it survived.
City walls exterior explanation + Golden Horn naval battle explanation + Fatih explanation of the "post-war city" + Topkapi explanation of the "Ottoman takeover" + Hagia Sophia exterior explanation