The architecture of Mesopotamia is ancient architecture of the region of the Tigris–Euphrates river system (also known as Mesopotamia), encompassing several distinct cultures and spanning a period from the 10th millennium BC, when the first permanent structures were built in the 6th century BC. Among the Mesopotamian architectural accomplishments are the development of urban planning, the courtyard house, and ziggurats. No architectural profession existed in Mesopotamia; however, scribes drafted and managed construction for the government, nobility, or royalty.