The investment of time and manpower devoted to the constructionof this complex would have resembled the work on a medievalcathedral. As early as 3600 BCE work had begun on the so-calledLimestone Temple in the Eanna precinct. Quarrymen and masonsremoved limestone from a rocky outcrop around fifty kilometers (31mi) to the southwest. Other men transported the stone to Uruk. Stillothers formed hundreds of thousands of mud bricks and clay cones,and set them out to harden in the sun. Others brought timber fromfar to the north for the roofs. Someone supervised all the workmenwho set the bricks and stones and mosaic cones in place. The menwould have been fed and provided for during the construction. Thebuilders were all probably residents of Uruk, united in their desire tocreate a magnificent home for their beloved divine queen.

But why is this blank? One interpretation  is that they left it blank to show that God,   the Supreme power has no definite shape, size  or form. Many people think Hinduism is only   about Idol worship and polytheism, but even during  ancient times, Hinduism acknowledged and discussed   00:05:19 other philosophies like God is formless, this is  called Nirakara & Nirguna during ancient times.   Hinduism even discusses atheism, theosophy

Kotilingeshwara Temple