The emperor Hadrian needed a summer home away from the bustle of Rome, and so Villa Adrianna was created in the year 125. The ruins here are in much better shape than what you'll find at Rome's Forum, and though much of the buildings and artwork has been pillored or destroyed, the quiet, undisturbed country seems to have been relatively untouched by the years.
Visiting Villa Adriana gives you more of a sense how the elite Roman society lived out their days than other collections of ruins for the buildings' shapes are often clear enough to reflect what they were used for in their time. My favorite sight was the small temple at the end of a reflecting pool, which seemed quite tranquil as evening began to fall.