Hangars with open superstructures often attract birds to nest and roost in. Graves were circular cylindrical superstructures made of stoned wall. Two Hotchkiss five-barrel revolving guns each were mounted on the fore and aft superstructures. Most were built of fired and mortared brick; some incorporated sun-dried mud-brick and wooden superstructures. Generally, Doric temples followed a tendency to become lighter in their superstructures. Its structure is thus inherited from these superstructures. Her metacentric height decreased to from her designed as a result of her enlarged superstructures. A framed structure with pile foundation is used in the superstructures. Superstructures are found above the main deck. The terrain was difficult to negotiate and contained old buildings and tomb superstructures. The superstructures are built using radar-absorbent synthetic materials. "Superstructures&colon; Engineering Marvels". Mark III mounts were also added, two each on the forward and rear superstructures. Mode used mainly for robotics applications and large superstructures. Great Wall is one of the largest superstructures in the observable universe.