GIACOMO DELLA PORTA. – Probably born in Lombardy c. 1540 and died in Rome in 1604. After a youthful period of activity in Genoa, where he is credited with the church of S. Maria Annunziata, he was continuously active in Rome from 1573, when he succeeded Vignola in the construction of the Gesù, modifying its design and making it the prototype of Counter-Reformation architecture. The same model was replicated by him on a smaller scale at S. Maria dei Monti (1584), while he departed from it in other works: the façade of S. Luigi dei Francesi (before 1583), S. Paolo alle Tre Fontane (1590), and the interior of S. Giovanni dei Fiorentini, where he resumed the arrangement by Sangallo, abandoning Michelangelo’s design.
He also succeeded Vignola as architect of the Vatican fabric, in which he did not depart from Michelangelo’s conception: under Gregory XIII he raised the chapel named after the Pope; and he continued the works under Sixtus V, working alongside Domenico Fontana, with whom he completed the dome, altering the master’s design only slightly. Confirmed in his post by Clement VIII, he executed for the Pope the Cappella Clementina, symmetrical to the Gregorian one, and the new confessio also called Clementine.
He also contributed to the construction of S. Atanasio dei Greci and probably also of S. Trinità dei Monti and S. Maria in Vallicella, and rebuilt the transept of S. Giovanni in Laterano. Among the civil buildings he erected, those for the Aldobrandini stand out: the palace in Piazza Colonna (later Chigi) and the villa in Frascati, both left unfinished at his death. He is also credited with the type of the sixteenth-century fountain in Rome, first realized in Piazza del Pantheon (1575).