It is easy enough to walk around the old and new towns. See below for details of transport to the Villa Romana.
The large Roman Villa is one of the highlights of Sicily, with the remains of a large number of rooms covered by a huge canopy to protect the numerous elaborate mosaics which are much more impressive than those at Pompeii. In fact you can tell what the room was by the mosaic. For instance, there is a mosaic with a rather rotund man getting a massage, then being washed down to enter the baths. After the baths the room shows the man drying off with a big fluffy towel. With that you know the first room was to get relaxed before entering the baths and so on. Also very interesting is the mosaic of the "Girls in Bikinis" depicting women working out in a gym.
The Villa sits 5km Southwest of Piazza Armerina, with about 5 buses a day from Piazza Senatore Mareschali, or you could walk, or take a taxi from the nearby Piazza Generale Cascino.
The town itself nestles on hills and was built in two parts - first by the Saracens in the 10th century and then developed to the southeast in the 15th and then again the 17th centuries. There are many wonderful buildings to see including the 18th century Duomo, which dominates the town standing majestically on top of a hill, the elegant town hall and grand old palazzi such as the Palazzo Trigona. For those who enjoy wandering through small streets and finding hidden places, try the 13th century area round the Via Monte near the Duomo. See: