When Nabonidus returned to Babylonia in 543/542 BC, he escalated his religious efforts and rebuilt the Ekhulkhul, the temple dedicated to Sîn in the major northern city of Harran.

[14] There is no evidence that Adad-guppi was a high-ranking priestess, as the only titles she claims in her inscriptions are "mother of Nabonidus" and "worshipper of Sîn, Ningal, Nusku and Sadarnunna".

[12] It is probable that Adad-guppi first came to Babylon as a prisoner after the Babylonians and Medes sacked Harran in 610 BC during the Medo-Babylonian conquest of the Assyrian Empire.

Herodotus's description of Nitocris contains a wealth of legendary material making it difficult to determine whether he uses the name to refer to Nabonidus's wife or mother.

[20] Michael B. Dick opposed Dalley's conviction in 2004, pointing out that even though Nabonidus did go to some length to revive some old Assyrian symbols (such as wearing a wrapped cloak in his depictions, absent in those of other Neo-Babylonian kings but present in Assyrian art) and attempted to link himself to the Sargonid dynasty, there is "no evidence whatsoever that Nabonidus was related to the Sargonid dynasty".

[35] Though Labashi-Marduk may have been the grandson of Nebuchadnezzar II through his mother, making him part of the royal bloodline, it is also possible he was the son of Neriglissar and a different wife.

[12] Nabonidus enjoyed consistent support from the Babylonian military throughout his reign and it is possible that the army played a role in his rise to the throne.

Belshazzar was the chief beneficiary of the entire affair, as he became the designated heir to the throne, and also inherited the large private estates of Labashi-Marduk, becoming one of the richest and most prominent men in Babylonia overnight.

[17] After celebrating the New Year's festival, Nabonidus embarked on a short trip to southern Babylonia, visiting the cities of Kish, Larsa, Uruk and Ur.

[44] One inscription suggests that Nabonidus went on a second successful campaign to Cilicia in 555 BC,[45] on the way perhaps attacking the city Hama in Syria,[46] but the record is fragmentary.

[48] Though the Elhulkhul was not restored until after Nabonidus returned from a long period of staying in Tayma in Arabia, it is possible that construction work started considerably earlier and it appears to have been his goal since he assumed the throne.

The Babylonians achieved victory relatively quickly, and Nabonidus still remained near the Anti-Lebanon Mountains in August, overseeing the transport of supplies back to Babylon.

[48] Modern archaeological excavations at Tayma has revealed that the city underwent considerable expansion during the 6th century, including the construction of an extensive irrigation system.

[55] However, stationing a Babylonian force at Tayma and leaving a governor in charge would have sufficed, the king would not have needed to stay in Arabia for ten years in order to pacify the region.

Due to the remote and inaccessible location of Tayma, an argument that Nabonidus intended to move the centre of gravity of his empire westwards, through constructing a new capital there, has no basis.

Per, Beaulieu: "unless one assumes that the king was totally devoid of strategic ability, it seems hard to believe that he would have engaged a significant part of the Babylonian army in a long campaign to Arabia without making sure that the northern and eastern borders of the empire would be secure, at least for a certain number of years".

Belshazzar as regent became acutely aware of the threat presented by Cyrus's growing Achaemenid Empire, as he is recorded as having expended resources at projects in Sippar and nearby defenses.

In addition to building inscriptions, the Verse Account of Nabonidus also alludes to attempts to establish Sîn as the foremost god of the Mesopotamian pantheon.

[73] Concrete evidence surrounding Nabonidus's religious ideas is relatively scarce and no surviving documents contain any theological foundations for the king's faith and beliefs.

Thus, Weiherhäuser and Novotny do not consider the evidence strong enough to support the idea that Nabonidus fanatically promoted Sîn, and sought to fully replace Marduk, within Babylonia itself.

[53][86] It is noteworthy that the festival was suspended in Nabonidus's absence given that it was effectively an annual reinstatement of Marduk's authority and was conducted to ensure the well-being of Babylon.

[77] After the celebration of the New Year's festival in 539 BC,[88] Nabonidus had the statues of the gods of Uruk,[89] Akkad,[90] Kish, Marad and Khursagkalamma brought to the capital for safety, the conventional first step in anticipation of attacks from the north-east.

It is possible the authorities at Sippar were disgruntled with Nabonidus's religious policies or else viewed the Babylonian defeat at Opis as so decisive that further resistance was pointless.

Cyrus the Great justified his conquest of Babylon by presenting himself as a champion divinely ordained by Marduk and by writing accounts of Nabonidus's "heretical" acts.

[106] After the fall of Babylon, a legend of Nabonidus having been mad, on account of his religious policies, gradually formed, which would eventually find its way into Hellenistic and Jewish tradition.

The story is similar to Mesopotamian traditions of kings being cursed by the gods with skin diseases and being forced to wander the arid steppes like wild animals.

There is a similar text from the Hellenistic period at Uruk, which ascribes Shulgi (r. c. 2094–2046 BC), a king of the Third Dynasty of Ur, as being cursed with a skin disease after desecrating Marduk and elevating Sîn in his place.

According to Beaulieu, the picture historians have of Nabonidus today is as a clearly able ruler, who tried to save the Neo-Babylonian Empire, a powerful but hastily built and politically unstable realm, from its internal instability and its desperate geopolitical position.

There is evidence that Nabonidus was more of an antiquarian than his predecessors, such as Nabopolassar and Nebuchadnezzar II, who conducted similar excavations during their restoration work on temples.

The reasoning for restoring the statue is thus not only attributed to religious factors, but also to an interest in Sargon as a king, and respect for the Akkadian Empire, the first imperial period of ancient Mesopotamia.