Sirmione was one of the busiest "mansio" (stops) along the Imperial road that traveled between Brescia and Verona and led to Gaul. Some buildings such as the Grottos of Catullus were probably used for housing and public storehouses. The ports were also important and used by many for trade on the lake Garda. With the fall of the Roman Empire, the peninsula also suffered the domination of the many barbarous populations that continually invaded Italy.
In 765 the noble Cuminondo was ordered by Kings Desiderio and Adelchi to pass on his riches to the basilicas of Sirmione. In June 774 Charlesmagne gave Sirmione on lake Garda to the abbey of San Martino di Tours. In 897 Carlomanno confirmed its immunity and privileges.

The peninsula of Sirmione was ruled by Verona in 1197, and in 1220 Emperor Frederick II granted Sirmione the right to fish along all shores of Lake Garda. In 1387 the town was ruled by the Visconti family. It later fell into the hands of Venice in 1405 and remained under its dominion until 1797. Sirmione became part of the Cisalpine Republic and subsequently joined the Lombardy-Veneto Kingdom from 1815 to 1859.

After a voyage in Bithnyia, Valerius Catullus (Verona 87 B.C - Rome 54 B.C.) returned to Sirmione on lake garda, where he owned a small home. The poem he wrote for the occasion is one of his most beautiful. Here is a translation by Thomas Hardy (1840 - 1928):
Sirmione, thou dearest dear of strands That Neptune strokes in lake and sea. With what high joy from stranger lands Doth thy old friend set foot on thee! Yea, barely seems it true to me that no Bithnyia holds me now, But calmly and assuringly Around me stretches homely Thou. Is there a scene more sweet than when Our clinging cares are undercast, And, worn by alien moils and men, The long untrodden sill repassed, We press the pined for couch at last, And find a full repayment there? Then hail, sweet Sirmio; thou that wast, And art, mine own unrivalled Fair!

It isn't easy to list all the famous people who were linked in some way to Sirmione. For example, among the habitués of Caffè Grande Italia in Piazza Carducci, the parlor par excellence of the peninsula of SirmioneGabriele D'Annunzio, Naomi Jacob, Tancredi Pasero, Maestro Arturo Toscanini, soprano Maria Callas, Mario Del Monaco, Renato Carosone and Arturo Benedetti Michelangeli.