My wife and I recently enjoyed a tour with Atakan in Istanbul during a cruise. Atakan took us to the Blue Mosque and the Hagia Sophia both of which are simply amazing. The Hagia Sophia, at almost 1500 years old, is among the most amazing places we've been. Having been repurposed multiple times it's steeped in history and is still in use today. Atakan's knowledge of the history and architecture really helped us to enjoy our day. His English is excellent too. We highly recommend this tour. Enjoy!