While I'm not very religious, I always appreciate hearing the call to prayer (adhan) in Islamic countries.
The lack of iconography in the mosques is also quite interesting and the subtle glow from the windows and lights is very beautiful. I like the use of light and color without relying on imagery.
Some of the mosques we visited smelled like feet since the tourists don't go through ablution before entering.
Also, be prepared if you want to visit the mosques to have a head covering and conservative clothing.
There's also St. Anthony of Padua Church in Beyoğlu tucked away on İstiklal Avenue.
I had no idea there was such a strong Italian presence, but it does make sense considering both Rome and Istanbul were such great powerhouses for religion and trading.