Memoirs of Hadrian by Marguerite Yournecar is a classic historical novel detailing the life and reign of the Roman emperor Hadrian, as told from the first-person point-of-view of Hadrian himself. The narrative is told in a letter written by the protagonist to his successor, Marcus Aurelius. It details the struggles and triumphs of a leader who made peace his central objective.

When Hadrian begins his letter to Marcus Aurelius, he is an old man dying from heart disease. He intends to give his adopted grandson a true history of his life and reign. Hadrian is born in Italica to a Spanish family. He studies rhetoric, Greek, philosophy and medicine in Spain and Greece, and trains as an army officer. During the waning days of Domitian's reign, he goes to Rome and works several years as a judge. There he lives a life of debauchery, until he returns to active duty in the Pyrenees.

While serving in Spain, Domitian dies and is succeeded by the elderly Nerva, who takes Hadrian's cousin Trajan as his adopted son. Nerva dies, and Hadrian is the first to tell his cousin of his accession. Trajan is uncertain of Hadrian's value and skills, but Hadrian proves himself in the Dacian Wars with acts of valor. Trajan tentatively chooses him as a successor. Hadrian marries into the family and is assisted by the empress, Plotina. Trajan begins a campaign of conquest in Parthia that dominates his reign. Hadrian believes his role as emperor should be to ensure peace and prosperity throughout the Roman world. Trajan dies and Hadrian takes the throne.

Hadrian does not care for Rome and spends most of his reign traveling the provinces. He makes peace with the Parthians, begins rebuilding Athens and Jerusalem, and builds centers of trade throughout the provinces. He also pushes reforms increasing imperial transparency and rights to slaves. While in Bithynia, he meets a beautiful Greek named Antinous and falls in love. The young man becomes his constant companion.

At about this time, Hadrian realizes he is divine. He begins to take his young lover for granted, and Antinous - knowing Hadrian's interest in cults and strange rites - sacrifices himself for the emperor. Hadrian is devastated, and he has Antinous interred in Alexandria. He builds hundreds of statues and sets about creating a cult to his dead lover.

Not long after, Jewish zealots in Jerusalem massacre Roman troops and send the city into revolt. Hadrian sends his best commander, but the battle continues for three years. Jerusalem is reduced to rubble, and the Jewish people become uniformly opposed to Roman rule. Hadrian wonders whether the Roman people are still worthy leaders of the world.

Upon returning to Rome after the Judea battle, Hadrian goes about choosing his successor. He settles on his friend Lucius Ceionius. Unfortunately, Lucius falls suddenly ill and dies. Hadrian then chooses a popular and able Senator, Antoninus, and a prodigious child of a renowned family, Marcus Aurelius, to succeed him. As Hadrian lies on his deathbed, be thinks back on his life and work. He has a achieved prosperity and peace in the Roman world and his lover is an established god, now. He dies contended.