When planning your itinerary, keep in mind the closures for these top sites:
Major attractions and shopping centers remain open for normal trading hours for the month of Ramazan (Ramadan, June 18-July 17, 2015; June 6-July 5, 2016; May 27-June 25, 2017), but they will close for half a day on the first day of religious holidays, with the indoor shops of the Grand Bazaar closing for the entire Şeker Bayramı (Sugar Holiday, three days immediately after Ramazan) and for the four days of Kurban Bayramı (Feast of Sacrifice, starting Sept. 23, 2015; Sept. 11, 2016; Sept. 1, 2017). It’s business as usual on public holidays.
The other day to avoid travel is May 1, when Istanbul comes to a standstill with road closures and public transportation shutting down to prevent May Day demonstrations.
Excerpted from the Second Edition of Moon Istanbul & the Turkish Coast.