The monastery was founded in 1658 by Costanza Severoli, a noble from Faenza, a widow of the Knight Giulio Piazza.
After the Napoleonic suppression took place in the early 800, which prohibited the profession of sacred vows and forced the Claustrals to abandon their residences, the nuns of the Monastery of the Holy Trinity found refuge with the Augustinian nuns who had survived the edict. Subsequently this site became municipal property and seat of the chancellery. In 1859, at the time of the Diocese of Modigliana, the building was enlarged and deeply renovated to be used as a seminary. Until that year, all the Modiglianese territory was part of the Diocese of Faenza.
