Being located halfway between Rome and Naples, Cassino can be easily reached:
Closest airports are Rome-Fiumicino, Rome-Ciampino, and Naples. From the airports go downtown Rome / Naples and get a bus or a train to Cassino.
Many trains serves Cassino from Roma Termini (Rome main train station). Trains are also available from Napoli Centrale (Naples main train station).
See Trenitalia’s website for time schedule and prices.
Take the A1-E45 highway which connects Milan to Naples, and use the Cassino exit.
If you like walking, let’s explore “The way of St. Benedict”, a path along history and nature, a journey of 300 km through the heart of Italy which starts in Umbria and ends up just in Cassino (you can skip some steps, though!).