On February 25, 138, the Emperor Hadrian adopted Antoninus Pius under condition that he adopt Marcus Aurelius in return. From the article:
"Hadrian
Hadrian was Roman emperor from 117 to 138 CE and he is known as the third of the Five Good Emperors (Nerva, Trajan, Hadrian, Antoninus Pius, and Marcus Aurelius) who ruled justly. Born Publius Aelius Hadrianus, probably in Hispania, Hadrian is best known for his substantial building projects throughout the Roman Empire and, especially, Hadrian’s Wall in northern Britain.
Early Life
As a young man, Hadrian was well educated in his hometown of Italica Hispania (modern day Seville, Spain) and left for Rome around the age of 14. His first military service was as Tribune under Emperor Nerva (r. 96-98 CE). When Nerva died, Trajan ascended to the throne. Emperor Trajan (r. 98-117 CE) was the first Roman ruler of provincial origin. Later biographers would attempt to place the birth of both Trajan and Hadrian in the city of Rome but both were of Hispanic ethnicity and this commonality has been assumed by some to be the reason for Trajan’s adoption of Hadrian as his successor (though most scholars dispute this).
Hadrian is commonly depicted in military attire even though his regime is marked by relative peace.
Trajan died on campaign in Cilicia in 117 CE, with Hadrian in command of his rearguard, and is not believed to have named a successor. Trajan’s wife, Plotina (who was fond of Hadrian) signed the papers of succession, and it is thought that she, not the emperor, was responsible for Hadrian’s adoption as heir. However that may be, it is known that Trajan respected Hadrian and had considered him as his successor even if he did not officially name him as such. Hadrian’s service to Trajan is well documented through the various important positions he held prior to becoming emperor of Rome.
Hadrian as Emperor
His popularity as emperor is attested to by the fact that Hadrian was absent from Rome for the better part of his reign. Earlier Roman rulers, such as Nero, were harshly criticized for spending less time away from the city. Professor D. Brendan Nagle writes:
[Hadrian] spent most of his reign (twelve out of twenty-one years) traveling all over the Empire visiting the provinces, overseeing the administration, and checking the discipline of the army. He was a brilliant administrator who concerned himself with all aspects of government and the administration of justice. (278)
His devotion to the army was such that he would sleep and eat among the common soldiers, and he is commonly depicted in military attire even though his regime is marked by relative peace.
Hadrian’s building projects are perhaps his most enduring legacy. He established cities throughout the Balkan Peninsula, Egypt, Asia Minor, and Greece. His love for Greece and Greek literature was such that he was known as 'Graeculus' (Greekling) in his youth, and his philhellenism did not dissipate with age. He visited Greece at least twice (probably more) and participated in the Eleusinian Mysteries, of which he was an initiate. The Arch of Hadrian, constructed by the citizens of Athens in 131/132 CE, honor Hadrian as the founder of the city. Inscriptions on the arch name Theseus (the traditional founder) but add Hadrian owing to the latter’s substantial contributions to Athens (such as the Temple of Zeus).
He dedicated a number of sites in Greece to his young lover Antinous, who drowned in the Nile River in 130 CE. Hadrian was deeply attached to Antinous and the young man’s death so greatly affected the emperor that he had him deified (from which the mystery cult in honor of Antinous grew). In Egypt, he founded the city of Antinopolis in his memory. In Rome, he rebuilt the Pantheon (which had been destroyed by fire) and Trajan’s Forum as well as funding construction of other buildings, baths, and villas. Many of these structures survived intact for centuries, some as late as the 19th century CE, and the Pantheon, still perfectly preserved, may be visited in the present day. Hadrian had a great interest in architecture and seems to have contributed ideas or even plans to the architects, though scholars no longer believe that he was the lead architect on any single project.
Hadrian's Wall
Of all his significant monuments and buildings, Hadrian’s Wall in northern Britain is the most famous. Construction of the wall, known in antiquity as Vallum Hadriani, was begun around 122 CE and corresponded to Hadrian’s visit to the province. It marked the northern boundary of the Roman Empire in Britain, but the length and breadth of the project (stretching, as it did, from coast to coast) suggests that the more important purpose of the wall was a show of Rome’s power. The wall was originally 9.7 feet wide (3 m) and 16-20 feet high (c. 6 m) east of the River Irthing, all built of stone, and 20 feet wide (6 m) by 11 feet high (3.5 m) west of the river, made up of stone and turf, stretching 73 miles (120 km) across uneven terrain.
It was built in six years by the legions stationed in Britain. There were between 14-17 fortifications along the length of the wall and a vallum (a ditch purposefully constructed of earthworks) which ran parallel to the wall. The Vallum measured 20 feet (6 m) wide by 10 feet (3 m) deep, flanked by large mounds of tightly packed earth. As Hadrian’s foreign policy was 'peace through strength', it is thought that the wall, which was originally plastered and whitewashed, would have clearly represented the might of the Roman Empire.
Jerusalem
Although Hadrian was a learned and cultivated man, his policy of peaceful relations and negotiations was not always adhered to. In 130 CE, Hadrian visited Jerusalem, which was still in ruins from the First Roman-Jewish War of 66-73 CE. He rebuilt the city according to his own designs and renamed it Aelia Capitolina Jupiter Capitolinus after himself and the king of the Roman gods. When he built a temple to Jupiter on the ruins of the Temple of Solomon (the so-called Second Temple, considered sacred by the Jews), the populace rose up under the leadership of Simon bar Kochba (also given as Shimon Bar-Cochba, Bar Kokhbah, Ben-Cozba, Cosiba or Coziba) in what has come to be known as the Bar-Kochba Revolt (132-136 CE). Roman losses in this campaign were enormous but Jewish losses were no less significant. By the time the rebellion was put down, 580,000 Jews had been killed and over 1000 towns and villages destroyed. Hadrian then banished the remaining Jews from the region and renamed it Syria Palaestina after the traditional enemies of the Jewish people, the Philistines. He ordered a public burning of the Torah, executed the Jewish scholars, and prohibited the practice and observance of Judaism.
Death & Successor
His health now failing, Hadrian returned to Rome and occupied himself by writing poetry and tending to administrative affairs. He named as his successor Antoninus Pius (r. 138-161 CE) on the stipulation that Antoninus would adopt the young Marcus Aurelius (r. 161-180 CE) to follow. Hadrian died in 138 CE, presumably of a heart attack, at the age of 62. He was buried first at Puteoli, on the grounds of the former estate of the rhetorician Cicero (as homage to Hadrian’s love of learning), but when Antoninus Pius completed the great Tomb of Hadrian in Rome the following year, his body was cremated and the ashes interred there with his wife and son. Antoninus Pius had Hadrian deified and temples built in his honor. The historian Gibbon writes:
[Hadrian’s rule was] the period in the history of the world during which the condition of the human race was most happy and prosperous…when the vast extent of the Roman Empire was governed by absolute power under the guidance of virtue and wisdom. (61)
Although Hadrian was not universally admired during his life, or since his death, his reign is generally considered in keeping with Gibbon’s estimation."