(b. 1634, Brusata, d. 1714, Roma)
Italian architect and engineer. Born in Lombardy, he arrived in Rome in the 1650s. In 1666, he became the "misuratore della R. Fabbrica di S. Pietro," and in 1697, he became the architect of Saint Peter's, Rome.
His prolific studio produced widely imitated designs for fountains, palaces, tombs, and altars, as well as the curved façade on the San Marcello al Corso. His many international students included Matthäus Daniel Poppelmann of Germany, James Gibbs of England, Filippo Juvarra of Italy, Johann Lucas von Hildebrandt and Fischer von Erlach of Austria, and others.
Fontana worked for Gian Lorenzo Bernini on Santa Maria dei Miracoli (1662-79) and finished Bernini's Palazzo di Montecitorio (formerly the Palazzo Ludovisi). His principal works in Rome are the Ginetti chapel at Sant' Andrea della Valle; the Cibo chapel in Madonna del Popolo; the cupola, great altar, and ornaments of the Madonna de' Miracoli, the church of the monks of Santa Marta; the façades of the church of Beata Rita and of San Marcolo in the Corso, the sepulchre of Queen Christina of Sweden in St. Peter's; the palaces Grimani and Bolognetti; the fountain of Santa Maria in Trastevere, and that in the piazza of St. Peter's which is towards Porta Cavallegieri.