The plaster model of Piazza Pius XII was made by the artist Pierino di Carlo from Abruzzo (1906-1992) in the 1930’s. Pierino di Carlo was already the creator of the famous scale model of Rome in the Constantine age known as Grande Plastico dell’Urbe (scale1:250) that is kept in the Museum of the Roman Civilization. The artist was known as one of the most talented artisans and scholars of this typology of architectural replica. The quintessence of the Vatican collections is divided in two sections and faithfully reconstructs the wide entry that connects Via della Conciliazione to St. Peters, and the buildings that delimit it. The prodigious technical competence with which this piece was made stands as witness to the vast experience that the artist had with material. At the same time, it is proof of the remarkable need the commissioner had. As an elevated quality was asked of Pierino Di Carlo, he responded by offering excellence with regards to the technical aspect: Di Carlo meticulously represents each and every architectural element, each ratio, molding, and proﬁle, while faithfully respecting the dimension of the project in scale. The two sections present a wooden framework and a “double level” in plaster in those parts which are not visible. Both are ﬁxed with vegetable ﬁbers. Thus, respecting the traditional techniques for the creation of plaster models.