Hadrian built his villa near the city Tibur (todays Tivoli) because he disliked Palatine Hill. Maybe there was too much noise and people for his taste. And he was not alone in these thoughts as many other emperors also felt that way. I guess also because the reason that Rome was a city of million people. That is the reason why Hadrian actually reigned his empire from Tibur in his later years. So all the court were living here with him. Here in Tibur palaces of Hadrian rested in peaceful anf beautiful scenery.
Hadrian ruled in Rome at the second and third decades of the 2nd century AD. Hadrian had been travelling as lot and he felt himself some architectural vision and interest. Therefore he took lot of time to take part to construction work himself.
After Hadrian many emperors used the villa for their refreshment. When Rome collapsed (500 AD) villa was left to deteriorate and it fell to ruins. And then Cardinal d’Este took marble stones and statues to decorate his own villa nearby – villa d’Este.
Because whole court was here, there need to be two bath-houses, hospital and many other household buildings.
PS. Remember! When you are in the city center of Tivoli you must be patient! There are really going yellow busses with number 4 to Hadrians villa! Wait, wait and wait. They will go there …finally.