This museum on the Golden Horn is perfect when you're overwhelmed by crowded tourist sites. It's huge, rarely crowded, and has fascinating exhibits about Turkish industrial history. Vintage cars, old submarines, steam engines - you can wander for hours without dealing with tour groups. The café overlooking the Golden Horn is peaceful, and the submarine exhibit lets you explore inside a real 1940s sub. Entry around 250 TL, typically open 10am-5pm weekdays and longer on weekends, closed Mondays. Take the ferry to Hasköy and walk 5 minutes.