Can go by plane to the two airports such as Fiumicino and Ciampino. And go to the city by the train from Austria, France ,Germany and others . And you can go to the city by cars or boat
And By thumb.( Hitchhiking in Italy is related with the 1960's hippies and "on the road" kind of culture. Therefore, it is considered out-dated and useless. You will almost never find Italians hitchhiking unless there's a serious problem with the bus or other means of transportation.)