The Phanar Greek Orthodox College is the oldest Greek school still running in Istanbul. It traces its line to 1454, the year after the Ottoman conquest, when the Patriarchate needed clergy and administrators it could train itself. For centuries its graduates rose into the Phanariots, the Greek elite of this hillside quarter, who supplied the empire with its chief interpreters and the governors of its Danube provinces. The red-brick building you see is much younger than the school. It was finished in the 1880s, paid for by the banker Georgios Zariphis, and it was designed to look like nothing else in the city: rampart-thick walls, turreted corners, and a great dome that was used as an observatory for astronomy lessons.
You cannot go inside. This is a working school, closed to visitors, so you look at it from the lanes below or from across the water. From the far bank of the Golden Horn the red mass stands clear above Fener's tiled roofs, and the brick glows when the low evening sun hits it. Behind the walls the school still teaches, but only a handful of students now use rooms built for hundreds — the plainest measure of how far Istanbul's Greek community has shrunk.