The town of Sirmione occupies the tip of a tiny peninsular that protrudes into the southern edge of Lake Garda in northern Italy. Its unique position makes it a popular tourist destination.
Sirmione is known to have been a popular resort town since the 1st century B.C.E., largely because of its thermal hot springs. Much of what you see in Sirmione today is newer, but there are Roman ruins in the historic center, too. The remains of a Roman villa are at the end of the peninsula, and are called the Grottoes of Catullus - the name of a Roman poet whose family lived in Sirmione in the 1st century B.C.E.
Another attraction is the Rocca Scaligera, a 13th-century castle. The picturesque and small historic center gets very crowded during the summer months, so if you can spend the night you may enjoy some peace and quiet.
Sirmione is roughly 80 miles from Milan, or about two hours on the faster train. You would need to take the train to nearby Desenzano del Garda, and then take a bus to Sirmione. It may seem easier (and faster) to drive, but because space is limited and the historic center is pedestrianized, parking can be very difficult.