: Dio frequently critiques the shift from merit-based adoption (like Hadrian's) to hereditary succession, famously noting that the Roman Empire descended from a "kingdom of gold to one of iron and rust" following the reign of Marcus Aurelius.

: The LacusCurtius site hosts the English translation by Earnest Cary, originally published in the Loeb Classical Library .

Cassius Dio’s Roman History ( Historia Romana ) is a monumental 80-volume work covering approximately 1,000 years, from the legendary arrival of Aeneas in Italy to 229 CE. Writing in Ancient Greek, Dio spent 10 years researching and 12 years composing his history while serving as a high-ranking Roman senator and two-time consul.

: Surviving largely through the 11th-century epitomes of John Xiphilinus and the 12th-century works of John Zonaras. Primary Access Points

: Nearly complete; these cover the critical period of 65 BCE to 12 BCE, detailing the collapse of the Republic and the rise of Augustus.

: Exist mostly as sparse fragments or summaries (epitomes).

For detailed research or reading, the following resources are highly recommended: