The Porta degli Angeli was an original Northern entrance to the Addizione Erculea.
It is built at the start of the region built as the Addizione Erculea.
The palace with its protruding marble portal and balcony, with a corner balcony, was designed and built in 1493-1498 by Biagio Rossetti as part of the Addizione Erculea.
As was usual for the eremitic, cloistered institutions, it was erected outside the city walls, but with construction of new walls, with the Addizione Erculea, it was enclosed in the city.
Among them are those in the north quarter ( especially the four at the intersection of its two main streets ), which was added by Ercole I in 1492 1505, from the plans of Biagio Rossetti, and hence called the " Addizione Erculea ".
A new part of the city, named Addizione Erculea ( " Erculean Addition " ) had been built in the previous century : it is commonly considered one of the major examples of urban planning in the Renaissance, the biggest and most architecturally advanced town expansion project in Europe at the time.