Roof apex: The roof apex of a large hall is usually topped with a ridge of tiles and statues for both decorative purposes as well as to weigh down the layers of roofing tiles for stability. These ridges are often well decorated, especially for religious or palatial structures. In some regions of China, the ridges are sometimes extended or incorporated into the walls of the building to form matouqiang (horse-head walls), which serve as a fire deterrent from drifting embers.