It is located in the old town of Istanbul for free. There are few tourists compared to the Blue Mosque and Hagia Sophia, but the interior of the mosque is very beautiful. I like it the most among the mosques I've been to. The window at the top of the entrance is a natural ventilation system to prevent the inside of the mosque from getting dirty with sous when the lights were lit using candles at that time. He politely explained Islam and the Suleimanie Mosque!