Hadrian arrived in Rome in the summer of AD 118, nearly a year after his actual succession to Trajan. His predecessor's eastern conquests had facilitated a massive Jewish revolt which required an in kind legionary response. While these revolts were largely quelled while Trajan was still alive, Hadrian was forced to finish the work. As one part of his ultimate resolution of the matter, Hadrian understood the difficulty in controlling the east beyond the Euphrates River and gave up Trajan's recent conquests.
While unpopular, especially to the legions that had brought these territories under Roman control with their blood, the desire to mark natural defensible borders necessitated the policy. In Dacia, however, whether he felt a need to deflect a growing sense of legionary resentment at his eastern withdrawal policy, desired continued economic control of Dacia's important mineral wealth (gold mines) or a combination of both, Hadrian confirmed and upheld Trajan's annexation of the territory.
Hadrian's eventual arrival in Rome was greeted with Senatorial hostility, thanks largely to the executions of four proconsular magistrates. As such, Hadrian focused on measures to increase his popularity with the masses. Numerous honors were voted upon Trajan (though more from the Senate than directly from Hadrian), massive debt was cancelled in an enormously popular public burning of the records, the port at Ostia was expanded to secure additional grain supplies and the alimenta (essentially providing government support to local communities) begun by Nerva and expanded by Trajan was continued. Building and restoration of public works throughout the empire was conducted on an unprecedented scale and Hadrian was an enormous patron of the arts and literature. Perhaps the most important achievement of Hadrian's reign was the reformation of the legal system. Conducted by Salvius Julianus (grandfather to future emperor Didius Julianus), these reforms included regular review of magisterial decrees and edicts ensuring that such measures provided desired and positive effects.
Despite his efforts, some reforms and projects (such as tearing down a theatre built by Trajan on the Campus Martius) were terribly unpopular. His poor relationship and lack of popularity with the senate, coupled with a strong desire to review the Empire's defenses, inspired him to leave the hostile city and explore the provinces first hand. In AD 121, Hadrian left Rome on an extended tour beginning to the north in Gaul. Form there he continued to Germania where the legions were drilled and trained in such a manner as to increase discipline that had grown lax. For centuries Roman armies had been raised only for temporary purposes involving conquest or defense from invaders. It was only during the imperial period that the legions became permanent standing forces that maintained static garrisons. As such, complacency from inactivity was a genuine concern. In addition to personally drilling the men (and performing such training right along with them), defense works were inspected, men of quality promoted and arrangements for military supply and logistics were settled.
From Germania, Hadrian continued north to Britannia where the matter of a defined controllable border was an ultimate concern. Unlike other frontier provinces such as Germania, which used the Danube and Rhine Rivers as natural borders, Britain had no such clearly marked and defensible position. Despite previous efforts to bring the far north under Roman control (under Agricola during the reign of Domitian) the logistical problems of asserting dominance over the scattered highland tribes made such efforts impractical. As northern Britain lacked a naturally defensible position, Hadrian ordered the situation remedied by the building of a massive wall to separate Rome from barbarian. Hadrian's Wall was built by legionaries (contrary to popular opinion, Roman armies rather than slaves had always been responsible for building not only defense works, but roads and sometimes aqueducts) in a massive effort that spanned eight years (AD 122 - 130).
The wall, stretching for 80 miles between modern Carlisle in the west and Newcastle in the east, was between 8 and 10 ft. thick and as high as 15 feet tall. Mile castles were built at 1 mile intervals (hence the name) and were garrisoned by auxilia (numbering approximately 9,000 men at any given time). Though the wall itself was a formidable defensive structure, its ultimate purpose was not truly to serve as a barrier, but as a deterrent to tribal aggression and perhaps more importantly, to act as a funnel forcing trade and civilian traffic through well regulated defensible positions.
From Britain, Hadrian continued south to Hispania and then to Mauretania in Northern Africa, where a revolt of the Moors was suppressed. From the African coastal city of Cyrene Hadrian continued east (which he preferred due its Hellenistic nature) visiting Crete, Syria, Pontus, Bithynia, Asia Minor and circling back through Thracia, Moesia, Dacia, Pannonia, Greece, Athens and Sicily before finally returning to Rome in AD 125. Spending just a few years in Italy, Hadrian was once again consumed by the 'wanderlust' and returned to Athens by AD 129. Hadrian held a fascination for Greek philosophy and culture and as such would visit Athens at least 3 times during his reign. The city too would benefit greatly from the emperor's patronage in the form of numerous building projects and improvements. The 'Greekling' as Hadrian came to be known, next journeyed from Athens back to Asia, then to Pamphylia, Phrygia, Cilicia, Syria, Cappadocia, Pontus, Antioch and Judaea by AD 130.
Hadrian's journey would continue to Egypt, again to Syria, Asia and Athens and eventually back to Rome in AD 132 but it was in Judaea that Hadrian's ambitious plans took a turn for the worse. In most of his provincial visits he was greeted enthusiastically thanks in part to gifts he offered to the populace, coupled with various public works projects. In the home of the Jews, however, there was a natural enmity carried over from the revolts during Trajan's reign and Hadrian paid little heed to the volatility of the region. First, he planned to rebuild Jerusalem (largely razed by Titus in AD 70) in the manner of a Roman city, complete with a temple to Jupiter where the Great Temple of Jerusalem once stood. While this affront to the religious sensibilities of the Jews passed without major incident, it planted the seeds of discontent. Two years later Hadrian, whose Hellenistic sensibilities found several strange Jewish customs to be repulsive, passed a law forbidding the Jewish practice of circumcision. As unrest began to stir, the collapse of the tomb of Solomon in Jerusalem due to Roman construction activity, was the final catalyst to set off wide spread revolt.
The revolt, led by Simon ben Kosiba (or Bar Kochba for 'son of star' indicating that ben Kosiba was considered a messiah), proved to be yet another difficult challenge for the Romans in Judaea. Lasting for 3 years (forcing Hadrian to return and remain in the east from AD 134 - 136), thanks in large part to the Jew's wise policy of avoiding direct large scale engagements with Roman legions, the destruction of the province and loss of life was devastating. According to Cassius Dio, nearly 1,000 Jewish villages and just fewer than 600,000 people were killed in various engagements. The Romans losses too were considerable. Having used at least 3 full legions, numerous auxilia and detachments from several other nearby legions it is assumed (because it disappears from historical records after this point) that at least one legion, XXII Deiotariana, was completely destroyed in the uprising and never reconstituted.
When the Romans were eventually victorious in AD 136, Hadrian's punishment was severe. Dead Jews were left unburied and to rot in the streets for years and many others were sold as slaves. Jewish temples were replaced by Pagan equivalents, Rabbis were imprisoned and executed, it was forbidden to teach Mosaic Law or to own religious scrolls and the people were forbidden even from entering Jerusalem. To drive the point home, the city was even renamed to Aelia Capitolina and Judaea itself to Palestinae. Following the brutal suppressions of both Trajan and Hadrian, the Jews had finally settled under Roman control and would never again rise up against them.