In addition to Hadrian's great provincial travels, and corresponding centralization of imperial government, Hadrian was an unrivaled patron of the arts and literature. Despite his extensive military background, certainly stemming from his relationship as a ward of Trajan, Hadrian was a student of Greek philosophy, culture and the arts.
In addition to his studies abroad, he was a writer (his autobiography is unfortunately lost) a poet and an architect of some note. Though criticism garnered from Trajan's famed architect Apollodorus regarding Hadrian's architectural style seemingly resulted in the master engineer's banishment and eventual execution. Hadrian's jealousy and ego in matters of the arts, accompanied by a fractured relationship with the Senate, certainly earned the emperor a legacy of disfavor among the societal elite.
Despite the criticism of Apollodorus and others, Hadrian's interests in architecture left Rome with some of its finest monuments including the completion of Trajan's forum. One masterpiece in particular, the Pantheon (AD 125) originally commissioned by Marcus Vipsanius Agrippa and destroyed by fire circa AD 80, was rebuilt according to Hadrian's specifications. Despite its conversion from Pagan temple to Christian church, it survives architecturally to this day largely as it was built 2 millenia ago and still serves as an operating church. The great dome, the centerpiece of the monument remained the largest in the world until the 20th century and is remarkable for the central circular opening (or oculus) which was representative of the sun and provides the interior's only light.
A new bridge, the Pons Aelius, led to Hadrian's grand mausoleum which was larger than that of even Augustus but was left uncompleted at the time of the emperor's death. Hadrian's wanderlust also inspired temples and construction projects throughout the empire. Athens in particular, the city of which he was most fond, was left with a great temple to Zeus (larger even than the Pantheon in Rome) that marked a boundary for a new city center. His wanderings also inspired Hadrian to recreate various buildings and structures from the provinces he visited. At perhaps his most elaborate and innovative series of architectural constructions, the Villa of Hadrian in modern Tivoli, approximately 100 buildings of various design and cultural influence were symbolic of the empire's far reaching power and Hadrian's love of architecture.
Hadrian was considered an expert in such fields as arithmetic, geometry, painting, music, poetry and literature. While his prowess in these fields may have been challenged by other contemporary 'experts' Hadrian's position of power and overbearing ego subjected these contemporaries to countless criticisms and abuses. Despite his great love and patronage of the arts much, his relationships with leading scholars of the day, like that with Apollodorus the architect, were precarious at best. Suetonius, the author of 'The Twelve Caesar's" was a leading secretary to Hadrian and was afforded access to imperial documents long since lost, before eventually being dismissed for indiscreet behavior with the empress (whom Hadrian had a cold and distant relationship with, perhaps affording reason why Suetonius was not executed).
Teachers of the day were subjected to all manners of ridicule and humiliation, despite greater training or knowledge in many cases, yet he constantly sought them out for discussion, debate and exchanges in poetry and philosophy. According to Aelius Spartianus and the debatable testament presented in the 'Historia Augusta' (which unfortunately is one of the few surviving written accounts of Hadrian) the emperor "bestowed both honors and riches upon all who professed these arts, though he always tormented them with his questions." In some cases, these various teachers and practitioners would be rewarded just prior to being dismissed from service.
Despite Hadrian's confusing behavior, he counted among his personal friends many members of the 'scholarly elite' including the philosophers Epictetus and Heliodorus and was an acquaintance of such authors as the previously mentioned Suetonius and Plutarch (famed for his 'Parallel Lives'). Perhaps the greatest example of these rather strange friendships, and the tolerance shown by Hadrian's so-called friends (as well as being indicative of the ambiguous nature of politics and survival during the Principate in general), again comes from Aelius Spartianus and his account of the philosopher Favorinus:
"And once Favorinus, when he had yielded to Hadrian's criticism of a word which he had used, raised a merry laugh among his friends. For when they reproached him for having done wrong in yielding to Hadrian in the matter of a word used by reputable authors, he replied: "You are urging a wrong course, my friends, when you do not suffer me to regard as the most learned of men the one who has thirty legions."