Kotte was a ''jala durgha'' (water fortress), in the shape of a triangle, with the Diyawanna Oya and Kolonnawa Oya marshes forming two long sides; along the shorter third (land) side a large moat (the 'inner moat') was dug. The fortress was nearly  in area, fortified with ramparts of ''kabook'' or laterite rock,  high and  in breadth.