The San Diego Franciscan monastery was commenced in 1559 and completed three years later. It was restored by the Franciscan Missionary Sisters of Mary. Among the municipal documentation are all rental contracts from 1868 onwards. From a technical point of view it is interesting due to an underground cistern beneath the cloister, built before the monastery in 1575 by Lombard workers. The architects and the Lombard masons confraternity of Sant'Ambrogio al Corso in Rome, were often called for the maintenance of the underground Salisano aqueduct.