A ziggurat was built as a solid core of sun dried mudbrick, cheap and abundant in a landscape without ready stone, faced on its exterior with a skin of harder, kiln fired baked brick set in bitumen to protect the softer core from rain and erosion. The core's bulk meant a ziggurat contained no internal rooms or passages of any size, unlike an Egyptian pyramid, which could enclose burial chambers; a ziggurat was solid mass built purely to gain height, with access provided by one or more monumental exterior staircases or ramps climbing its terraced sides to a shrine at the summit.
The best preserved example, the Great Ziggurat of Ur, built under the Third Dynasty of Ur in the late third millennium BCE and restored in antiquity by the Babylonian king Nabonidus, still stands to a considerable height in modern Iraq and shows the triple staircase arrangement converging at a gate partway up the structure.
The Etemenanki, the ziggurat of Babylon dedicated to the god Marduk, was according to ancient description considerably larger still, though its physical remains are far more fragmentary than those at Ur. Because ziggurats were rebuilt, restored and sometimes enlarged by successive rulers over many centuries, the structure visible at any given site typically represents the latest of several superimposed building phases rather than a single original construction.