According to Paul the Deacon, Imola was in 412 the scene of the marriage of Ataulf, King of the Visigoths, to Galla Placidia, daughter of Emperor Theodosius the Great.

This and the following centuries witnessed incessant wars against the Ravennatese, the Faentines and the Bolognese, as well as the internecine struggles of the Castrimolesi (from Castro Imolese, "castle of Imola") and the Sancassianesi (from San Cassiano).

Pope Benedict XII turned the city and its territory over to Lippo II Alidosi with the title of pontifical vicar, the power remaining in the family Alidosi until 1424, when the condottiero Angelo della Pergola, "capitano" for Filippo Maria Visconti, gained the supremacy (see also Wars in Lombardy).

It was again brought under papal authority when it was bestowed as dowry on Caterina Sforza, the bride of Girolamo Riario, nephew of Pope Sixtus IV.

This proved advantageous to Imola, which was embellished with beautiful palaces and works of art (e.g. in the cathedral, the tomb of Girolamo, murdered in 1488 by conspirators of Forli).

The rule of the Riarii, however, was brief, as Pope Alexander VI deprived the son of Girolamo, Ottaviano, of power, and on 25 November 1499, the city surrendered to Cesare Borgia.

The city has dedicated multiple memorials and public spaces to Ayrton Senna and Roland Ratzenberger, who lost their lives in the circuit during the 1994 San Marino Grand Prix.

[citation needed] The city's professional soccer team, Imolese Calcio 1919, plays in a stadium located inside the Circuit, "Stadio Romeo Galli".