[2] At Forlì, Riario erected the fortress of Rocca di Ravaldino, one of the strategically most important strongholds of the Romagna.

In the course of this feud he had the papal protonotary, Lorenzo Colonna, arrested and tortured to death, a deed which provoked much enmity against his family in the city.

[4][5] After the death of Pope Sixtus IV, Riario, as commander of the papal forces, returned to Rome with his wife Caterina.

She entered the Castel Sant' Angelo with troops in order to put pressure on the cardinals to elect a candidate conformable to the Riarios' interests.

After 10 days of chaos in Rome, Riario concluded with the terrified cardinals that he would withdraw his troops and his wife's occupation of the castello in return for 7,000 ducats in cash.

In 1488, he was the last of the main Pazzi conspirators left alive, and was himself assassinated in a conspiracy led by two members of the Orsi family from Forlì, supposedly over a financial dispute.