We took the bus up to Rumelifeneri, a tiny town built around a lighthouse (named Rumeli Feneri) at the northern end of the Bosphorus, so on both the Black Sea and the Bosphorus. Rumeli is the former name for the Turkish lands in Europe and feneri means "lighthouse."
Rumelifeneri is a district in Istanbul province, and the city bus runs up to the town. Not a bad trip, and it gave us the chance to see what Istanbul looks like outside its core.
There's a Biennial artwork up here, which is what gave us the idea to visit. But the chance to see the Black Sea and the end of the Bosphorus is what really motivated us. (Wait until you see the artwork!)
