There are quite a few hotels from Marriott portfolio in Istanbul, but only one in the historical location opened so far. I stayed (paid, not a redemption) at Orientbank by Autograph Collection. It is a nice hotel (former bank), but I had a few issues there (very loud AC; one front desk agent disagreed on everything - from prior to arrival communication to denial everything I asked in person-fortunately, everybody else was nice; dumpsters right by the windows, and workers stay pretty much all night with trucks loading - the hotel doesn`t have control over it since it is the center of the city, etc). I might come back again only because of the location, but if those two new hotel open soon, I am willing to give it a try.