My question here is - did Rome ever really have a cohesive code of "freedom, virtue and honor" to lose?

As a student of ancient history, the closest example of these ideals in early Roman empire was the first emperor, Augustus, who instituted the Pax Romana (where conquered lands that Rome held would be allowed to integrate their cultural practices into Roman life, without persecution, so long as they paid taxes and didn't challenge Roman rule). He encouraged the arts ("finding Rome a city of brick, leaving it a city of marble), preached conservative sexual morality (very family focused) mixed with giving benefits to the poor, and once he had defeated Mark Antony and Cleopatra, mainly focused on consolidation of the empire rather than unsustainable endless expansion.

In his own person, he also affected an air of humility, refusing honors (although some think this was a clever reverse psychology strategy to avoid being assassinated the way his adopted father Julius Caesar was, he essentially manipulated the Senate into begging him to remain in power by constantly threatening to renounce it). He was not known for the lavish excess of later Julio-Claudians, living a fairly simple lifestyle without much in the way of finery and grandeur.

However while much of Augustus's life was admirable, and certainly his influence on Rome was better than any other emperor in that he set the empire up for long term stability and prosperity among the people - the early emperors were not known for being paragons of morality.

The second emperor, Tiberius was known for cruelty alongside competence in other areas. Caligula was initially beloved and seemed to show great promise, but later (some think after a brain injury or infection) had a major personality change and became psychotic, erratic and flagrant. He was the first "bad emperor". Claudius was weak, although he was not cruel or crazy like Caligula. Nero is the most famous "bad emperor" of them all.

So was "virtue" really such an important feature of the early Roman empire (the time when it was most successful and stable)? I think you can point to more examples where it failed to live up to its ideals even from the beginning.

I mean, it also contained the rot within it of slavery. Even in Augustus' time - freedom only meant freedom for certain kinds of men. Despite the power of some women like Empress Livia, Vestal Virgins or Eumachia of Pompeii, most women were seen as homemakers only and their fathers were allowed to choose whether to let them live or die when they were born, or to sell them into slavery. Even if the girls were allowed to grow up, they didn't have a choice as to whom they could marry - Augustus famously used his own daughter Julia as a bargaining chip to secure alliances and try to develop his own dynasty, he married her off to multiple people including one person she hated (Tiberius) then had her arrested when she cheated on Tiberius. He then exiled her to a remote island for defying him, and didn't allow her visitors unless he'd vetted them all. This persisted until his death, and then Tiberius made her exile even more horrible so she would be destitute and likely perished from hunger or disease.

So I think the so-called "virtues of Rome" were far from spotless, and I don't think we can see a clear or linear "decline in morality" throughout the Empire. Sure some periods allowed for better conditions for the poor, or for captured territories, or for religious minorities. But overall - Rome was rife with violence, sexism and slavery. Gladiatorial combat where countless animals were killed and many people were killed was the chief form of entertainment for the masses (although many gladiator fights were similar to WWE today in that they were staged - many still died, often prisoners of war, slaves or convicts).

I find Rome endlessly fascinating but not so much because the history of Rome is the story of a fall from an exulted and idealised civilisation, but because Rome shows how people back then lived so differently and yet so similarly to today. We are still bloodthirsty people. Still cruel. Still idealistic, still wanting to be virtuous. Still creative. Still diverse and ever-changing.

Rome has so much historical material and it's not so far in the past that we have lost it all to time. I visited Pompeii nine years ago and it brought the past so vividly to live that these people really lived and were so much like us.