Nuruosmaniye Mosque is Istanbul's first Baroque mosque, and the break shows the moment you look at it. Straight lines give way to undulating cornices, swept arches and stone carved as if it were soft. The courtyard is a horseshoe, a semicircle of columns found on no other imperial mosque in the city. Inside, a single wide dome floats over a room ringed with tier upon tier of windows, so daylight pours in from every side and catches the gilded calligraphy.
It was finished in 1755, abandoning the sober geometry of Sinan's classical age for the curves of European Baroque, and the name means the light of Osman. You approach up a broad flight of steps onto a raised terrace, the mosque lifted clear above the surrounding streets. One of its gates opens straight onto the Grand Bazaar, so the hush of prayer sits a few steps from the loudest commerce in the old city. It still works as a mosque, with its fountain, library and tombs on the same terrace.