(b. 1762, Roma, d. 1839, Roma)
Italian architect, urban planner, and designer, part of a family of artists. He was a chief exponent of Neoclassicism in Italy.
He occasionally provided designs for silver and also designed some furnitures and other decorative arts, such as the rock crystal and silver reliquary for relics of the Holy Crib in Santa Maria Maggiore, for Pope Pius IX. Valadier worked in Rome and elsewhere in the Papal States, but many of his projects remained on paper.
He was named official architetto camerale of the Papal States by Pope Pius VI in 1786. He taught architecture at the Accademia di San Luca, he was a pioneer archeologist and a restorer of monuments, such as the Milvian Bridge (1805) and the Arch of Titus in Rome, (1819-21). He retraced the ancient line of the Via Flaminia (1805) and restored Vignola's neglected Church of Sant'Andrea in Via Flaminia, which influenced his own Church of Santa Maria della Salute in Fiumicino, the newly-established port for Rome.
Among his other major works were: clocks with mosaic faces on top of the façade belltowers, Basilica of Saint Peter (1786-90); general plan for access to the Imperial Forums (1811); general plans for Piazza del Popolo (first plans, 1793; final plans executed 1816-20), creating its elliptical plan and linking it via stairs and terraces with the Pincio, including the Casina Valadier (1813 onwards); Teatro Valle (1819); Fiumicino, the first planned suburb of modern Rome (1822-28); general plan for the piazza of St John Lateran.
He published collections of his designs and drawings in several volumes from 1807 to 1834.