Süleymaniye mausoleum, resting place of 16th century sultan Süleyman, beside Süleymaniye mosque.
Also a mausoleum beside Hagia Sophia. This one was closed, but outside it were interesting artworks (apparently featuring an ancient era QR code?!).
Lǎowā 15mm f/4 macro lens and Rokinon 8mm f/3.5 fisheye lens, Sony α77 camera.