<P> The background glazes are mainly a vivid blue, which imitates the color of the highly - prized lapis lazuli . Gold and brown glazes are used for the animal images . The borders and rosettes are glazed in black, white, and gold . It is believed that the glaze recipe used plant ash, sandstone conglomerates, and pebbles for silicates . This combination was repeatedly melted, cooled, and then pulverized . This mixture of silica and fluxes is called a frit . Color - producing minerals, such as cobalt, were added in the final glaze formulations . This was then painted onto the bisque - fired bricks and fired to a higher temperature in a glaze firing . </P> <P> After the glaze firing, the bricks were assembled leaving narrow horizontal seams from one to six millimeters . The seams were then sealed with a naturally - occurring black viscous substance called bitumen, like modern asphalt . The Ishtar Gate is only one small part of the design of ancient Babylon that also included the palace, temples, an inner fortress, walls, gardens, other gates and the Processional Way . The lavish city was decorated with over 15 million baked bricks, according to estimates . </P> <P> Once per year the Ishtar Gate and connecting Processional Way were used for a New Year's procession, which was part of a religious festival celebrating the beginning of the agricultural year . In Babylon, the rituals surrounding this holiday lasted twelve days . The New Year's celebrations started immediately after the barley harvest, at the time of the vernal equinox . This was the first day of the ancient month of Nisan, equivalent to today's date of March 20 or 21 . </P> <P> The Processional Way, which has been traced to a length of over half a mile, extended north from the Ishtar Gate and was designed with brick relief images of lions, the symbol of the goddess Ishtar (also known as Inanna). Worshipped as the Mistress of Heaven, Ishtar represented the power of sexual attraction and was thought to be savage and determined . Symbolized by the star and her sacred animal the lion, she was also the goddess of war and the protector of ruling dynasties and their armies . The idea of protection of the city is further incorporated into this gateway design by the use of crenelated buttresses along both sides to this entrance into the city . </P>

Where was the ishtar gate erected and what was its purpose