Upon entering through the sentries gate we turn left, where the first of the three towers built under the vezirs stands, with a collection of old cannon in front. This is the Halil Paşa tower. Its inner diameter is 23,30 metres, the inside one 10 metres, so we must conclude the walls are 6,5 metres or so thick. The external diameter higher up is 15,50 meters and the walls slim to a mere 2,8 metres. The height is 33 metres. It is not round, but 12-sided and has (had, looked pretty empty inside) six floors.