How to go to Sultanahmet from Istanbul Airport

You should use HAVAIST IST-20 SULTANAHMET TO ISTANBUL NEW AIRPORT BUS to reach Sultanahmet from Istanbul Airport. There are HAVAIST buses that run very often on this route. These buses allow you to travel with the comfort of an intercity bus. You can find the timetable in following article: https://isturkeysafe.com/ISL-istanbul-airport-by-bus. Note that HAVAIST is the only public transporation available right now to reach Istanbul Airport from Sultanahmet(and vice versa). There is no subway, metro or tram on this route.