Marcus Aurelius was born in Rome in 121 AD. and reigned from 161 to 180 AD. in a period in which the barbarian invasions intensified and the problems related to the security of the empire's borders became accentuated.
The emperor Hadrian, who had understood his talents, had him adopted as successor by Antoninus Pius (Marcus Aurelius married his daughter Faustina), together with Lucius Verus (son of Lucius Aelius Caesar).
Upon the death of Antoninus Pius, Marcus Aurelius associated Lucius Verus with the empire and effectively created a dyarchy, as it was at the time of the Republic.

Marcus Aurelius was a cultured emperor and philosopher, author of the famous «Conversations with himself», a collection written in Greek, probably not intended for publication. They are autobiographical philosophical meditations that concern questions as old as the world: the meaning of life and man's impotence in the face of the will of the gods. Following the teachings of the Stoics, Marcus Aurelius wrote: «We must fight to the limit of our abilities and endure suffering with patience and perseverance».

Although life's events are predestined, the emperor nevertheless believed that thanks to willpower and discipline something could be changed for the better: «Try to understand, before it is too late, that you possess something higher in yourself, and divine, than the simple instincts that move your emotions and make you move like a puppet».

Following the conciliatory policy of Antoninus Pius, Marcus Aurelius chose to respect the Senate and its powers, trying to choose the right persons; in the provinces he introduced regulations to supervise tax collectors, and tried to prevent corruption.
He promoted several judicial reforms, reduced the number of gladiatorial shows and delayed their times so that they did not interfere with everyday work.
«But what then has value? Elicit applause? Certainly not. Nor even arouse the praise of the crowd, which is nothing more than applause of the tongue."

The state coffers, however, were empty, due to the numerous donations, the enormous military expenses to which were added the effects of a serious economic and demographic crisis also caused by a plague that caused many deaths, perhaps even Marcus Aurelius himself. He reduced the expenses of the imperial court and tried to administer wisely, even putting imperial properties and precious personal objects up for sale or auction.

From the beginning of his reign, unfortunately, he had to engage in long and bloody wars, to repress rebellions or face barbarian invasions throughout the empire. In the East, the Parthians invaded Armenia, inflicting harsh defeats on the Roman armies, following which Lucius Verus was joined by experienced generals, who turned the tide of the conflict.

Armenia was occupied by the Romans in 163-164 AD, and in 166 Marcus Aurelius and Lucius Verus celebrated the triumph in Rome on the Parthians. Their sons Commodus and Annius Verus (still children) also took part in the event and were appointed Caesars on that occasion. A preview of Diocletian's Tetrarchy.

Another front also opened to the north: in 166 AD. the Danube was crossed by powerful and  Germanic warrior tribes who intended to settle within the borders of the empire because they in turn were pressured by other nomadic peoples. In 169 Lucius Verus died suddenly in Altino. In 170 AD the Quadi and the Marcomanni inflicted harsh defeats on the Romans, destroyed Oderzo and went so far as to besiege Aquileia.
It took years to regain control of those territories; the decisive victory over the Marcomanni occurred in 178 AD. during the last military campaign of Marcus Aurelius, who died in Sirmium or Vindobona on 17 March 180.

To try to solve the problem of the recurring invasions, Marcus Aurelius allowed many barbarians to settle in Dacia, Pannonia, Moesia, Germany and even Italy, assigning them cultivable lands in order to have the new farmers and soldiers he needed. A solution that led to the gradual "barbarization" of the Roman army, and on the log period undermined it from inside.

His son Commodus was named associate Augustus in 177 AD, and succeeded his father in 180. He immediately wanted to return to Rome to perform in gladiatorial combat and dedicate himself to a dissolute life, as mentioned in contemporary ancient sources. His crazy conduct highlighted the risks associated with dynastic succession, a recurring and crucial problem for the empire since the time of Augustus. For more than a century the previous emperors had all been chosen and appointed through the adoption system; but in the absence of alternatives Marcus Aurelius chose his son, returning to family and dynastic succession with all the inconveniences that followed.

To remember Marcus Aurelius and his victories over the Danubian barbarians, Commodus had a Column similar to that of Trajan erected, the Antonine Column which was surmounted by a statue of the emperor, later replaced by that of the apostle Paul. It illustrates the wars against the Marcomanni and the Sarmatians, with 116 episodes and has a spiral staircase inside, just like Trajan's Column.

Marcus Aurelius is also known for the famous gilded bronze statue, one of the very few remaining from antiquity, whose original location is unknown. In 1539 it was placed by Michelangelo in the center of the Piazza del Campidoglio which he designed. In 1997 it was replaced by a copy and the original was placed in a special pavilion inside the Capitoline Museums.