Foundation No.5 of Erlitou Site located in middle east of the palace area,which was paralleling to Foundation No.3 in east and west.Two remains were large-sized rammed-earth foundation of Phase II of Erlitou Culture.Foundation No.5 covered 2700 sq m currently,without wall.The foundation contained four layers of courtyards,in which buried several contemporaneous burials of aristocrats.Foundation No.5 would be the earliest and best in conservation large-sized rammed-earth courtyards having two or more layers,of which showed the distinction of palace architecture in early Erilitou Culture.It was the origin of the later palace architecture in courtyards of China.