The most often visited places are Tarquinia or Ostia Antica. Tarquinian Tombs are very interesting as you can see how many of the ancient burial themes were adopted and expanded upon by the Etruscans. The local museum was also excellent. Don't miss the "Tarquinian Horses". Depends whether you are more interested in the Romans (Ostia Antica) or Etruscans (Tarquinia). You might get prettier scenery on the Tarquinia tri.