Ziggurat
A ziggurat is a form of monumental architecture originating in ancient Mesopotamia which usually had a rectangular base and was built in a series of steps up to a flat platform upon which a temple was raised. The ziggurat was an artificial mountain raised for the worship of the gods to elevate the priests toward heaven.
The people of the Ubaid Period (c. 5000-4100 BCE) are thought to have come down from the mountains to the plains of Mesopotamia and influenced the Sumerians (or were Sumerians), the first to build ziggurats as religious sites mirroring sacred high places. This is speculative, of course, but suggested by Sumerian names of some ziggurats which reference mountains. The structure was known as unir in Sumerian and as ziggurratum (or ziggurartu) in Akkadian, both meaning “peak,” “pinnacle,” or “high place,” and served as a platform on which priests would perform rituals in view of the people far below.