Zahir Spa is located in a beautiful hotel. The spa is located in the lower level and not that big, but it was clean and well designed. I had a hammam/scrubbing and massage at Zahir Spa, which was great. Both services were in completely private rooms, which is what I wanted. It was a good massage experience, but my experience afterwards was bad.
The locker room had many lockers but it is in a tiny room, so I believe that only one person can use it at a time. After my massage, a lady was using the locker for around 15-20 min, so they had me wait in the spa lobby. The problem is that I was only wearing a towel around my waist, which was uncomfortable and awkward because the spa lobby was a public area. I guess I could have asked to wait in a more private area, but I also didn't know that the wait was 15-20 min long; thought it would be quick.
When I went to pay, I believe the owner (or someone in charge) was at the front desk (because owners usually have a different demeanor compared to regular staff). She started telling me about her views on why Turkey has high inflation, Ukraine invasion, and other world events that I didn't agree with. We were both civil, but I ended up spending another 20 min there defending my views.
Good massage and nice proximity to Istiklal street, but I won't be going back.