He came from Lombardy, for a short time worked in Florence, and then in 1708 at the age of eighteen came to Rome, where he found employment in the well-known workshop of Camillo Rusconi. Together with the master, for whom he worked for the next twenty years, he took part in the decorations of the Church of Sant’Agnese in Agone. He completed works according to the designs of his supervisor, as well as other sculptors of the time, e.g. Pietro Bracci. He also participated in decorating St. Peter’s Basilica (San Pietro in Vaticano).

However, he created his most spectacular works in the Basilica of St. John in the Lateran (San Giovanni in Laterano) in the chapel of the Corsini family, from which Pope Clement XII came. In completing the pope’s figure Maini patterned his work on the work of Gian Lorenzo Bernini, just as he did in creating the seized by convulsive shivers St. Anne in the Church of Sant’Andrea delle Fratte. In this last work, using all of the artistic resources of the divine Bernini, the artist presented the figure of an old, dying woman. It must be admitted that, such a far-reaching naturalism was at the time of the dominant courtly elegance something truly revolutionary, and certainly refreshing.

After 1730 a period of particular recognition of Maini’s works began, while he himself was counted among the greatest artists of his times. A testimony to his greatness was, unfortunately to a large extent destroyed by an earthquake,   the commissions for the royal court of Portugal.

The most important Roman works of Giovanni Battista Maini:

•       Church of Sant’Agnese in Agone – funerary monument of Innocent X and the allegories of virtues accompanying him – Faith and Justice, two angels in the finish of the main altar, 1730
•       Basilica San Giovanni in Laterano (Corsini Chapel) – funerary monument of Cardinal Neri Corsini (1734), tombstone statue of Pope Clement XII, 1736
•       Basilica San Pietro in Vaticano – statue of St. Francis of Paola (1732) and St. Philip Neri, 1736
•       Church Santi Luca e Martina – reliefs showing symbols of St. John the Evangelist and St. Luke in the pendentives of the church dome
•       Church of Sant’Andrea della Fratte – statue of the lying St. Anne, two angels
•       Church of Santa Maria della Scala – marble angels above the altar in the chapel of St. Theresa
•       Basilica Santa Maria Maggiore – allegory of Humility above the entrance portico of the church and (in the interior) relief Gelasius burns heretical books
•       Church of San Luigi dei Francesi – image of Pope St. Gregory I the Great in the pendentives of the church dome, 1752
•         Church of Santa Maria in Publicolis – funerary monument of Scipione Publicola Santacroce, 1750