Take a half-day Bosphorus cruise and leave the city center behind. With a guide, you'll float up the Bosphorus and pass by historic buildings, including Dolmabahce Palace, Ciragan Palace, and Rumeli Fortress. Enjoy a lunch of mezes aboard the boat before you disembark in the Beykoz neighborhood. After that, you can walk in the hills of Beykoz and explore the area before heading back to the city center.