Why do you think the Sumerians would want the ziggurat to be highly visible?

The ziggurat is the most distinctive architectural invention of the Ancient Near East. Like an ancient Egyptian pyramid, an ancient Near Eastern ziggurat has four sides and rises up to the realm of the gods. However, unlike Egyptian pyramids, the exterior of Ziggurats were not smooth but tiered to accommodate the work which took place at the structure as well as the administrative oversight and religious rituals essential to Ancient Near Eastern cities. Ziggurats are found scattered around what is today Iraq and Iran, and stand as an imposing testament to the power and skill of the ancient culture that produced them.

One of the largest and best-preserved ziggurats of Mesopotamia is the great Ziggurat at Ur. Small excavations occurred at the site around the turn of the twentieth century, and in the 1920s Sir Leonard Woolley, in a joint project with the University of Pennsylvania Museum in Philadelphia and the British Museum in London, revealed the monument in its entirety.

What Woolley found was a massive rectangular pyramidal structure, oriented to true North, 210 by 150 feet, constructed with three levels of terraces, standing originally between 70 and 100 feet high. Three monumental staircases led up to a gate at the first terrace level. Next, a single staircase rose to a second terrace which supported a platform on which a temple and the final and highest terrace stood. The core of the ziggurat is made of mud brick covered with baked bricks laid with bitumen, a naturally occurring tar. Each of the baked bricks measured about 11.5 x 11.5 x 2.75 inches and weighed as much as 33 pounds. The lower portion of the ziggurat, which supported the first terrace, would have used some 720,000 baked bricks. The resources needed to build the Ziggurat at Ur are staggering.