Yusuf Ziya Mansion, also known as Perili Kosk, is a striking Bosphorus mansion near Rumeli Hisari. The building now houses Borusan Contemporary, so a visit combines modern art with one of the waterfront's more unusual historic houses.
Its "haunted mansion" nickname comes from the long period when parts of the building stood unfinished. Go for the architecture, the contemporary exhibitions, and the views across the strait.