I. Structure
The easiest structure to identify in Hadrian's Villa is the Pecile, also known as the Poikile. It would be very difficult to miss either the large shimmering pool or the impressive rectangular colonade that encloses it. (1) The western side of the colonade is of a double porch, while the other three sides serve to border the esplanade and pool. A bit less visible is the Hundred Chambers, or Cento Camerelle, which consists of dozens of rooms beneath the esplanade of the Pecile. In addition, to keep the rooms from becoming too humid, there was a hollow double wall separating them from the adjacent hill. (2)
Figure 1
Figure 2
II. Modern Interpretations
Inscriptions found on the tufa and brick-constructed double porch of the Pecile provide evidence of its former function. These passages include the instructions of doctors that a porch be constructed to allow for after-dinner walks. The actual length of the porch corresponds to their advised distance, of around 429 meters. An added feature of the porch is its usefulness in a variety of climate conditions. The double-sided structure can provide either shade or allow for a stroll in the warm sun, depending on the current weather. (3)
To run such a large estate, as well as to protect it, a large number of servants and soldiers were needed. This is where the Hundred Chambers came in. The lower quality and vast amount of rooms in the Chambers help identify them as the living quarters of the Villa's serving class.
Figure 3
III. Wider Context
Many believe that Hadrian modeled the Pecile after the Stoa Poikile in Athens. It's not too much of a stretch on the imagination to figure out where this theory comes from. Both structures are long colonnaded hallways, similiar in size and shape, not to mention function. It seems likely that the well-traveled Emperor would have modeled the Pecile after popular Greek architecture, and this was by no means a unique occurance in the Villa. See Hall with Doric Pillars.