(b. 1690, Messina, d. 1748, Roma)
Italian architect, nephew of Filippo Juvarra. He moved from Sicily to Rome where he studied under Ludovico Gregorini (1661-1723) together with the latter's son Domenico Gregorini (c.1700-1777). After the death of Ludovico Gregorini in 1723, Domenico inherited his father's studio and Pietro and Domenico collaborated closely in the remainder of their lives, so much so that it is difficult to distinguish the contribution of either of the two architects in the numerous activities in which they took part.
Passalacqua and Gregorini carried out several commissions for Cardinal Ottoboni (1667-1740), grandnephew of Pope Alexander VIII and a great patron of art. In the circle of the cardinal, they deepened their knowledge in the fields of set design, and Baroque theater festival. The two architects also received numerous commissions from Cardinal Aldrovandi, then Governor of Rome. However, the Passalacqua and Gregorini names remain linked mainly to the renewal of the Basilica of Santa Croce in Gerusalemme (1741-44), an ancient church whose restoration was one of the last major enterprises of Baroque Rome.