Babylon's standing as a holy city rested on Marduk and on the temple complex of Esagila at its centre, beside the stepped tower Etemenanki, whose name means the foundation of heaven and earth. The Enuma Elish tells how Marduk alone agreed to fight the sea goddess Tiamat when the older gods would not, how he was granted supreme kingship in return, and how he made the world from her body and built Babylon as a resting place for the gods. The poem is a theology of empire as much as an account of creation: it explains why the god of one city should stand at the head of a pantheon he had not originally led.
The akitu festival at the start of the spring month of Nisan bound the king to that story. Ritual texts describe him brought before the statue of Marduk, stripped of his insignia, struck on the cheek by the high priest and made to declare that he had not neglected the city or its temple, before the regalia were returned to him. He then took the god's hand and led the statue in procession along the Processional Way and out through the Ishtar Gate to a festival house beyond the walls. Chronicles record years in which the festival could not be held as a failure of the whole order, and note that it lapsed for years together while Nabonidus was absent from the city.
Robert Koldewey's excavations from 1899 uncovered the walls, the gate and the processional street, and the reconstructed Ishtar Gate stands in Berlin. The site itself has been damaged repeatedly, most recently by military occupation, and was inscribed on the World Heritage list in 2019.