While surveying Byzantine buildings in Trabzon, I took the opportunity of measuring these three interesting Turkish buildings; and publish the plans, with some brief notes on their construction, in the hope that the drawings at least may be of some use to someone qualified to make a real study of them. Hatuniye Camii, Figs. 1-5 : This mosque, standing in an open space just outside the old city, beyond the west ravine and the bridge spaiming it, was built in memory of Gülbahar Sultan, mother of Selim I (1512 - 20) and wife of Bayazit II (1481 - 1512). Plan and Construction. It is kept in excellent repair. The masonry is of well-dressed dark grey stone which varies to pinkish-grey, with narrow mortar joints; the roofs are lead-covered. The central square of the plan is covered by a dome on pendentives; the east and west wings each have a smaller dome; the porch (fig. 3), stretching the full width of the north side, is five bays long, each with a dome. The six column.s supporting the porch are of Marmara marble and the capitals have a formalised leaf motif. The two niches in the porch wall of the mosque have stalactite carving, as has the recess over the doorway; none of it is very deeply cut.