Final answer:
The son of Catherine the Great was Paul I of Russia. He was followed by his son Alexander I, who was succeeded by Nicholas I and later by other Romanov rulers like Alexander II.
Step-by-step explanation:
The son of Catherine the Great was Paul I of Russia. Catherine the Great's reign was an era characterized by expansion and the power politics of the Enlightenment, where she became known as an "enlightened despot." Paul succeeded Catherine II after her reign and was known for his attempts to reform the Russian government based on the principles of Enlightened absolutism.
His rule, however, did not last long as he was assassinated in a coup, and his son, Alexander I, ascended to the throne in 1801. It is Alexander I who was present at the Congress of Vienna, maintaining a deeply conservative and mystic belief in his role as a monarch empowered by divine right. Despite Paul I being the immediate son of Catherine the Great, it was his descendants, including Nicholas I and Alexander II, who continued the Romanov dynasty's rule over Russia with varied approaches to its immense challenges, including modernization and resistance to social upheaval.