The ingenuity of the Roman people but not really
The narrator and the Kings and Emperors mentioned in the book all boast about the ingenuity of the Roman people and how no other nation can compare with them. Ironically, however, as the narrator points out, this is not true since most of the things and ideas the Romans claimed as being their own were actually taken from other nations and cultures.
Saving the Empire and being killed for it
Julius Cesar, probably the most famous Roman leader who ever lived, died assassinated by his own people. What is ironic in this instance is not his death, but rather the fact that he was killed for saving and protecting the Roman Empire.
Committing suicide
A large number of historical figures mentioned in the book ended up eventually committing suicide for various reasons. The fact that they decided to commit suicide is ironic because culturally, this practice was associated with the poor. However, what we see here is that the ruling class became involved in such practices as well.
Democracy will bring forth peace
One of the reasons why the Roman leaders pushed for democracy was because they believed it will bring a period characterized by peace and prosperity. Ironically, however, we see that the opposite has happened and that period was above all violent and unstable.
No women
Women were perceived as seen as being second class citizens, with no power whatsoever. As such, women were ignored when it came to taking important decisions and were seen as incapable of rational thought. Because of this, it is ironic to see how countless women saved the nation throughout history, even though they were told they could never do it.